Multilayered polyolefin-based films having an integrated backsheet and encapsulation performance comprising a layer comprising crystalline block copolymer composite or block copolymer composite

ABSTRACT

A multilayer film structure including a top encapsulation layer A, a tie Layer B between top Layer A and bottom Layer C and a bottom layer C, the multilayer film structure characterized in that tie Layer B includes a crystalline block composite resin or a block composite resin and bottom Layer C includes a polyolefin having at least one melting point greater than 125 C.

This application claims priority from provisional U.S. Patentapplication 61/503,326 filed Jun. 30, 2011 having the same title as thisapplication; from U.S. patent application Ser. No. 61/570,464 filed Dec.14, 2011 entitled, “FUNCTIONALIZED BLOCK COMPOSITE AND CRYSTALLINE BLOCKCOMPOSITE COMPOSITIONS AS COMPATIBILIZERS” and from U.S. patentapplication Ser. No. 61/570,340 filed Dec. 14, 2011 entitled,“FUNCTIONALIZED BLOCK COMPOSITE AND CRYSTALLINE BLOCK COMPOSITECOMPOSITIONS”. This application is related to commonly assigned and U.S.Patent application Ser. No. 61/503,335 filed the same date herewith andentitled “MULTILAYERED POLYOLEFIN-BASED FILMS HAVING A LAYER COMPRISINGA CRYSTALLINE BLOCK COPOLYMER COMPOSITE OR A BLOCK COPOLYMER COMPOSITE”and claiming priority from provisional U.S. Patent application61/503,335.

This invention relates to films having a crystalline block copolymercomposite or block copolymer composite layer and having improvedcombinations of properties; being particularly suited for use as anintegrated or combined protective backsheet and encapsulation layer inelectronic device (ED) modules, e.g., photovoltaic (PV) modules. In oneaspect, the invention relates to the backsheet/encapsulation films foruse in such modules. In another aspect, the invention relates toco-extruded, multilayered films of this type. In still another aspect,the invention relates to the ED module incorporating such abacksheet/encapsulation film.

Thermoplastic polymeric material films, often referred to as plasticfilms, are commonly used as layers in the manufacture of modules orassemblies comprising one or more electronic devices including, but notlimited to, solar cells (also known as photovoltaic (PV) cells), liquidcrystal panels, electro-luminescent devices and plasma display units.The modules often comprise an electronic device in combination with oneor more substrates or layers, often positioned between two substrates orlayers, in which one or both of the substrates comprise, as support(s),glass, metal, plastic, rubber or another material. The terminology forthe names and descriptions of the ED component layers varies somewhatbetween different writers and different producers but polymeric filmmaterials are typically used as internally located “encapsulant” or“sealant” layers for the device itself or, depending upon the design ofthe device, as outer “cover” or “skin” layer components of the module.

PV modules are well known in the art, and typically comprise thefollowing layer components that are assembled into the final modulestructure:

-   -   1. a stiff or flexible transparent cover layer,    -   2. a front transparent encapsulant,    -   3. a PV (solar) cell,    -   4. a rear encapsulant (typically the same composition as the        front encapsulant) and    -   5. a backsheet.        Another possible PV module design using a backsheet layer is:    -   1. a stiff transparent cover layer such as glass    -   2. a cell material deposited onto the stiff transparent cover        layer    -   3. an encapsulant layer    -   5. a backsheet

The present invention is concerned with improved integrated backsheetfilms or film layers that utilize a crystalline block copolymercomposite or block copolymer composite layer and combine the functions(relative to a conventional PV module structure) of a rear encapsulantlayer with the backsheet layer and in turn provide improved PV modulesin terms of cost effectiveness and performance. Backsheet layers, asdiscussed in more detail below, protect the back surface of the cell andmay have additional features that enhance the performance of the PVmodule.

Examples of some of the types of backsheet products that are currentlyin commercial use are TPE-type structures (a PVF/PET/EVA laminate)available from Madico, and Icosolar 2442 (a PVF/PET/PVF laminate)available from Isovolta; and PPE-type structures (PET/PET/EVA) structureavailable from Dunmore. A number of proposed improved and enhancedbacksheets are also disclosed including the following.

In U.S. Pat. No. 6,521,825 solar cell module backsheet layers aredisclosed having two heat and weather resistant layers with a moistureresistant core layer.

In U.S. Pat. No. 7,713,636B2 multi-layer films comprisingpropylene-based polymers are disclosed having improved peel strengthproperties and comprising a core layer and a first tie layer made fromat least 5 wt % of a grafted propylene-based polymer.

WO 2010/053936 discloses backsheet layers for electronic device (ED)modules, e.g., photovoltaic (PV) modules, having at least three layersincluding a tie layer of a glycidyl methacrylate graft resin joininglayers that each use a maleic anhydride modified resin (MAH-m resin) ineach of the joined layers to provide good interlayer adhesion.

US 2011/0048512 discloses backsheet layers for electronic device (ED)modules, e.g., photovoltaic (PV) modules, comprising a coextrudedmultilayer sheet that comprises: i) an inner layer comprising apolyolefin resin; ii) a core layer comprising a polypropylene resin, ablend of a polypropylene resin and a maleic anhydride graftedpolypropylene (MAH-g-PP), or a polypropylene resin/MAH-g-PP multilayerstructure; iii) an outer layer comprising a maleic anhydride graftedpolyvinylidene fluoride (MAH-g-PVDF), a blend of a polyvinylidenefluoride (PVDF) and a MAH-g-PVDF, or a PVDF/MAH-g-PVDF multilayerstructure; iv) a first tie layer between the core layer and the outerlayer; and v) an optional second tie layer between the core layer andthe inner layer.

In WO/2011/009568 there are disclosed photovoltaic module backsheets onbase of preferably high molecular weight, impact resistant, shrinkageand thermal (flow) resistant FPP (Flexible Polypropylene) compositionspreferably containing functional particles or being coextruded with aprimer adhesive layer to obtain highly reliable adhesion on EVA adhesivelayers. In one embodiment, the backsheet has a functionalized polyolefin(PO) adhesive layer allowing direct adhesion to cells back-contacts,i.e. without the use of an EVA adhesive layer. In a further embodiment,the backsheet, with functional PO adhesive layer, allows the use of anupper adhesive layer which has a transparent thermoplastic polyolefin(TPO) film layer.

Noting the issues and limitations involved with the use of the prior artcomponents in electronic devices such as PV modules, there is always acontinuing desire for improved and lower cost electronic devices such asPV modules that can be obtained by use of improved components in theirconstruction. One particular improvement that is thought to increaselifetime of PV modules is better interlayer adhesion of integratedbacksheet sufficient in magnitude to substantially reduce or eliminateinterlayer failure, i.e., delamination, between backsheet layers in PVmodules.

SUMMARY OF THE INVENTION

Therefore, according the present invention there is provided amultilayer film structure comprising a top encapsulation Layer A, abottom Layer C and a tie Layer B between Layer A and Layer C, themultilayer film structure characterized in that Layer B comprises acrystalline block copolymer composite (CBC) or a specified blockcopolymer composite (BC), comprising: i) an ethylene polymer (EP)comprising at least 40 mol % polymerized ethylene; ii) analpha-olefin-based crystalline polymer (CAOP) and iii) a block copolymercomprising (a) an ethylene polymer block comprising at least 40 mol %polymerized ethylene and (b) a crystalline alpha-olefin block (CAOB), ora mixture of said composite(s); and bottom Layer C comprises apolyolefin having at least one melting point greater than 125° C. In anumber of the alternative embodiments related to the selection of blockcomposite resins there are provided such film structures where the i) EPin tie Layer B comprises at least 80 mol % polymerized ethylene and thebalance polymerized propylene; the block composite resin in tie Layer Bis a crystalline block composite resin; the tie Layer B block compositeresin has a CAOB amount (in part (iii)) in the range of from 30 to 70weight % of the CAOB, preferably in the range of from 40 to 60 weight %of the CAOB and/or tie Layer B comprises a CBC having a CBCI of between0.3 to 1.0 or a specified BC having a BCI of between 0.1 to 1.0.

Alternatively, in Layer B in such films, propylene is the alpha-olefinin ii) and iii) in tie Layer B and the CAOP is a copolymer of propyleneand ethylene; tie Layer B comprises a blend comprising greater than 40weight percent CBC or specified BC, such blend preferably furthercomprising one or more polyolefin selected from an ethylene octenecopolymer plastomers or elastomer, LLDPE and LDPE; and/or the CBC orspecified BC of Layer B has a melt flow rate of from 3 to 15 g/10 min(at 230° C./2.16 Kg).

Alternatively in a further embodiment, the invention is a multilayerfilm structure as described above in which the top encapsulation Layer Acomprises an ethylene octene copolymer plastomers or elastomer,preferably a silane-graft containing ethylene octene copolymer.

Further alternative embodiments include such films as described abovewherein the bottom Layer C comprises a propylene-based polymer,preferably a propylene-based polymer having a heat of fusion value of atleast 60 Joules per gram (J/g).

In one embodiment the present invention is such a multilayer filmstructure comprising a top encapsulation Layer A comprising asilane-graft-containing ethylene alpha olefin copolymer, a bottom LayerC comprising a propylene-based polymer and a tie Layer B between Layer Aand Layer C comprising a crystalline block copolymer composite (CBC)comprising i) an ethylene polymer (EP) comprising at least 93 mol %polymerized ethylene; ii) a crystalline propylene polymer and iii) ablock copolymer comprising (a) an ethylene polymer block comprising atleast 93 mol % polymerized ethylene and (b) a crystalline propylenepolymer block and preferably the Layer B is a blend further comprisingone or more polyolefin selected from an ethylene octene copolymerplastomers or elastomer, LLDPE and LDPE.

In another embodiment of the present invention such multilayer filmstructures according to claim 1 have a thickness of from 0.2 to 1.5 mmwherein Layer A is from 0.15 to 1.25 mm in thickness; Layer B is from 10to 150 μm thickness; and Layer C is from 150 to 375 μm in thickness.

Another embodiment includes electronic device (ED) modules comprising anelectronic device and such films as described herein. A furtherembodiment is a lamination process to construct a laminated PV modulecomprising the steps of:

-   -   (1.) bringing at least the following layers into facial contact        in the following order:        -   (a) a light-receiving top sheet layer having an exterior            light-receiving facial surface and an interior facial            surface;        -   (b) a light transmitting thermoplastic polymer encapsulation            layer, having one facial surface directed toward the top            sheet layer and one directed toward a light-reactive surface            of a PV cell;        -   (c) a PV cell having a light reactive surface;        -   (d) a backsheet layer comprising a multilayer film structure            according to claim 1; and    -   (2.) heating and compressing the layers of Step (1.) at        conditions sufficient to create the needed adhesion between the        layers and, if needed in some layers or materials, initiation of        their crosslinking.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an exemplary PV module having athree-layer integrated backsheet in adhering contact with the backsurface of an electronic device.

DETAILED DESCRIPTION

One of the important features of the films of the present invention isuse of a tie layer that comprises a block composite comprising: i) anethylene-based polymer; ii) an alpha-olefin-based crystalline polymer(which is preferably based on propylene) and iii) a block copolymercomprising an ethylene block and a crystalline alpha-olefin (preferablypropylene) block. In discussing the polymer components of the filmlayers and films of present invention there are several terms that arefrequently used and are defined and understood as follows.

Polymer Resins Descriptions and Terms

“Composition” and like terms mean a mixture of two or more materials,such as a polymer which is blended with other polymers or which containsadditives, fillers, or the like. Included in compositions arepre-reaction, reaction and post-reaction mixtures the latter of whichwill include reaction products and by-products as well as unreactedcomponents of the reaction mixture and decomposition products, if any,formed from the one or more components of the pre-reaction or reactionmixture.

“Blend”, “polymer blend” and like terms mean a composition of two ormore polymers. Such a blend may or may not be miscible. Such a blend mayor may not be phase separated. Such a blend may or may not contain oneor more domain configurations, as determined from transmission electronspectroscopy, light scattering, x-ray scattering, and any other methodknown in the art. Blends are not laminates, but one or more layers of alaminate may contain a blend.

“Polymer” means a compound prepared by polymerizing monomers, whether ofthe same or a different type. The generic term polymer thus embraces theterm homopolymer, usually employed to refer to polymers prepared fromonly one type of monomer, and the term interpolymer as defined below. Italso embraces all forms of interpolymers, e.g., random, block, etc. Theterms “ethylene/α-olefin polymer” and “propylene/α-olefin polymer” areindicative of interpolymers as described below. It is noted thatalthough a polymer is often referred to as being “made of” monomers,“based on” a specified monomer or monomer type, “containing” a specifiedmonomer content, or the like, this is obviously understood to bereferring to the polymerized remnant of the specified monomer and not tothe unpolymerized species.

“Interpolymer” means a polymer prepared by the polymerization of atleast two different monomers. This generic term includes copolymers,usually employed to refer to polymers prepared from two or moredifferent monomers, and includes polymers prepared from more than twodifferent monomers, e.g., terpolymers, tetrapolymers, etc.

“Polyolefin”, “polyolefin polymer”, “polyolefin resin” and like termsmean a polymer produced from a simple olefin (also called an alkene withthe general formula C_(n)H_(2n)) as a monomer. Polyethylene is producedby polymerizing ethylene with or without one or more comonomers,polypropylene by polymerizing propylene with or without one or morecomonomers, etc. Thus, polyolefins include interpolymers such asethylene/α-olefin copolymers, propylene/α-olefin copolymers, etc.

“(Meth)” indicates that the methyl substituted compound is included inthe term. For example, the term “ethylene-glycidyl (meth)acrylate”includes ethylene-glycidyl acrylate (E-GA) and ethylene-glycidylmethacrylate (E-GMA), individually and collectively.

“Melting Point” as used here (also referred to a melting peak inreference to the shape of the plotted DSC curve) is typically measuredby the DSC (Differential Scanning calorimetry) technique for measuringthe melting points or peaks of polyolefins as described in U.S. Pat. No.5,783,638. It should be noted that many blends comprising two or morepolyolefins will have more than one melting point or peak, manyindividual polyolefins will comprise only one melting point or peak.

Layer C—High Melting Point Polyolefin Resins

The polyolefin resins useful in the bottom layer or Layer C of thebacksheet have a melting point of at least 125° C., preferably greaterthan 130 C, preferably greater than 140° C., more preferably greaterthan 150° C. and even more preferably greater than 160° C. Thesepolyolefin resins are preferably propylene-based polymers, commonlyreferred to as polypropylenes. These polyolefins are preferably madewith multi-site catalysts, e.g., Zeigler-Natta and Phillips catalysts.In general, polyolefin resins with a melting point of at least 125° C.often exhibit desirable toughness properties useful in the protection ofthe electronic device of the module.

Regarding polyolefin resins in general, such as suitable for Layer C orfor other polymer components of the present invention, the sole monomer(or the primary monomer in the case of interpolymers) is typicallyselected from ethylene, propene (propylene), 1-butene,4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene,1-tetradecene, 1-hexadecene, and 1-octadecene and is preferablypropylyene for the Layer C polyolefin resin. If the polyolefin resin isan interpolymer, then the comonomer(s) different from the first orprimary monomer is/are typically one or more α-olefins. For purposes ofthis invention, ethylene is an α-olefin if propylene or higher olefin isthe primary monomer. The co-α-olefin is then preferably a differentC₂₋₂₀ linear, branched or cyclic α-olefin. Examples of C₂₋₂₀ α-olefinsfor use as comonomers include ethylene, propene (propylene), 1-butene,4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene,1-tetradecene, 1-hexadecene, and 1-octadecene. The α-olefins for use ascomonomers can also contain a cyclic structure such as cyclohexane orcyclopentane, resulting in an α-olefin such as 3-cyclohexyl-1-propene(allyl cyclohexane) and vinyl cyclohexane. Although not α-olefins in theclassical sense of the term, for purposes of this invention certaincyclic olefins, such as norbornene and related olefins are α-olefins andcan be used as comonomer in place of some or all of the α-olefinsdescribed above. Similarly, styrene and its related olefins (forexample, α-methylstyrene, etc.) are α-olefins for purposes of comonomersaccording to this invention. Acrylic and methacrylic acid and theirrespective ionomers, and acrylates and methacrylates are also comonomerα-olefins for purposes of this invention. Illustrative polyolefincopolymers include but are not limited to ethylene/propylene,ethylene/butene, ethylene/1-hexene, ethylene/1-octene, ethylene/styrene,ethylene/acrylic acid (EAA), ethylene/methacrylic acid (EMA),ethylene/acrylate or methacrylate, EVA and the like. Illustrativeterpolymers include ethylene/propylene/1-octene,ethylene/propylene/butene, ethylene/butene/1-octene, andethylene/butene/styrene. The copolymers can be random or blocky.

The high melting point polyolefin resins (having a melting point of atleast 125° C.), that are useful in the present invention and preferredfor use as all or most of bottom layer Layer C in the practice of thisinvention include propylene-based polymers, also referred to aspropylene polymers or polypropylenes, including e.g., polypropylene orpropylene copolymers comprising a majority of units derived frompropylene and a minority of units derived from another α-olefin(including ethylene). These propylene-based polymers includepolypropylene homopolymer, copolymers of propylene and one or more otherolefin monomers, a blend of two or more homopolymers or two or morecopolymers, and a blend of one or more homopolymer with one or morecopolymer, as long as it has a melting point of 125° C. or more. Thepolypropylene-based polymers can vary widely in form and include, forexample, substantially isotactic propylene homopolymer, random propylenecopolymers, and graft or block propylene copolymers.

The propylene copolymers comprise at least 85, more typically at least87 and even more typically at least 90, mole percent units derived frompropylene. The remainder of the units in the propylene copolymer isderived from units of at least one α-olefin having up to 20, preferablyup to 12 and more preferably up to 8, carbon atoms. The α-olefin ispreferably ethylene or a C₃₋₂₀ linear, branched or cyclic α-olefin asdescribed above.

The following are illustrative but non-limiting propylene polymers thatcan be used in the backsheets of this invention: a propylene impactcopolymer including but not limited to former DOW PolypropyleneT702-12N; a propylene homopolymer including but not limited to formerDOW Polypropylene H502-25RZ; and a propylene random copolymer includingbut not limited to former DOW Polypropylene R751-12N. It should be notedthat the propylene polymer products above and other that were formerlyavailable from The Dow Chemical Company may now be available fromBraskem or correspond to products available from Braskem. Otherpolypropylenes include some of the VERSIFY® polymers formerly availablefrom The Dow Chemical Company, the VISTAMAXX® polymers available fromExxonMobil Chemical Company, and the PRO-FAX polymers available fromLyondell Basell Industries, e.g., PROFAX™ SR-256M, which is a clarifiedpropylene copolymer resin with a density of 0.90 g/cc and a MFR of 2g/10 min, PROFAX™ 8623, which is an impact propylene copolymer resinwith a density of 0.90 g/cc and a MFR of 1.5 g/10 min. Still otherpropylene resins include CATALLOY™ in-reactor blends of polypropylene(homo- or copolymer) with one or more of propylene-ethylene orethylene-propylene copolymer (all available from Basell, Elkton, Md.),Shell's KF 6100 propylene homopolymer; Solvay's KS 4005 propylenecopolymer; and Solvay's KS 300 propylene terpolymer. Furthermore,INSPIRE™ D114, which is a branched impact copolymer polypropylene with amelt flow rate (MFR) of 0.5 dg/min (230° C./2.16 kg) and a melting pointof 164° C. would be a suitable polypropylene. In general, preferredpropylene polymer resins include hompolymer polypropylenes, preferablyhigh crystallinity polypropylene such as high stiffness and toughnesspolypropylenes including but not limited to INSPIRE™ 404 with an MFR of3 dg/min, and INSPIRE™ D118.01 with a melt flow rate of 8.0 dg/min (230°C./2.16 kg), (both also formerly available from The Dow ChemicalCompany). Preferably the propylene polymer MFR (230° C./2.16 kg, dg/min)is at least 0.5, preferably at least 1.5, and more preferably at least2.5 dg/min and less than or equal to 25, preferably less than or equalto 20, and most preferably less than or equal to 18.

In general, preferred propylene polymer resins for Layer C have heat offusion values (reflecting the relatively higher crystallinity) asmeasured by DSC of at least 60 Joules per gram (J/g), more preferably atleast 90 J/g, still more preferably at least 110 J/g and most preferablyat least 120 J/g. For the heat of fusion measurements, the DSC is rununder nitrogen at 10° C./min from 23° C. to 220° C., held isothermal at220° C., dropped to 230° C. at 10° C./min and ramped back to 220° C. at10° C./min. The second heat data is used to calculate the heat of fusionof the melting transition.

Propylene polymer blend resins can also be used where polypropyleneresins as described above can be blended or diluted with one or moreother polymers, including polyolefins as described below, to the extentthat the other polymer is (i) miscible or compatible with thepolypropylene, (ii) has little, if any, deleterious impact on thedesirable properties of the polypropylene, e.g., optics and low modulus,and (iii) the polypropylene constitutes at least 55, preferably at least60, more preferably at least 65 and still more preferably at least 70,weight percent of the blend. The propylene polymer can be also beblended with cyclic olefin copolymers such as Topas 6013F-04 cyclicolefin copolymer available from Topas Advanced Polymers, Inc. withpreferred amounts when used between 2, 4, and 8 weight percent tobetween 40, 35 and 30 weight percents. In general, preferred propylenepolymer resins for Layer C comprise an impact modifier such as ethyleneoctene plastomers such as AFFINITY PL 1880G, PL8100G, and PL 1850G brandresins or ethylene octene elastomers such as ENGAGE 8842, ENGAGE 8150,and ENGAGE XLT 8677 brand resins commercially available from The DowChemical Company, olefin block copolymers such as for example INFUSE9100 and 9107 brand resins commercially available from The Dow ChemicalCompany or propylene based elastomers such as VERSIFY 2300 and VERSIFY3300 brand resins available from Braskem. In general, these are used inamounts at least of 2 weight percent, preferably at least 5 and morepreferably at least 8 weight percent and preferably less than 45, 40 and35 weight percents Other candidate impact modification or blend resinsare ethylene/propylene rubbers (optionally blended with polypropylenein-reactor) and one or more crystalline block copolymer composite orblock copolymer composites as described herein. Combinations of impactmodifiers of different types may also be used.

Other additives that could be used with the propylene polymer resins areinorganic fillers such as talc or epoxy coated talc, colorants, flameretardants (halogenated and non-halogenated) and flame retardantsynergists such as Sb₂O₃.

Layer B Crystalline Block Copolymer Composite or Block CopolymerComposite Resin Components

According to the present invention, it has been found that the use as atie layer of certain types of new crystalline block copolymer composites(CBC's) or block copolymer composites (BC's) provides improved filmstructures and films. The use of the layer comprising the specified CBCand/or BC provides improved combinations of adhesive and other physicalproperties in multilayer film structures that can provide both backsheetand encapsulation layer performance in assembling laminate electronicdevice modules.

The term “block copolymer” or “segmented copolymer” refers to a polymercomprising two or more chemically distinct regions or segments (referredto as “blocks”) joined in a linear manner, that is, a polymer comprisingchemically differentiated units which are joined (covalently bonded)end-to-end with respect to polymerized functionality, rather than inpendent or grafted fashion. In a preferred embodiment, the blocks differin the amount or type of comonomer incorporated therein, the density,the amount of crystallinity, the type of crystallinity (e.g.polyethylene versus polypropylene), the crystallite size attributable toa polymer of such composition, the type or degree of tacticity(isotactic or syndiotactic), regio-regularity or regio-irregularity, theamount of branching, including long chain branching or hyper-branching,the homogeneity, or any other chemical or physical property. The blockcopolymers of the invention are characterized by unique distributions ofboth polymer polydispersity (PDI or Mw/Mn) and block lengthdistribution, due to the effect of shuttling agent(s) in combinationwith the catalyst(s) employed in their preparation.

As used herein, the terms “block composite” (“BC”), “block copolymercomposite resin,” “block copolymer composite” and the like refer to apolymer comprising (i) a soft ethylene copolymer, polymerized units inwhich the comonomer content is greater than 10 mol % and less than 90mol % and preferably greater than 20 mol % and less than 80 mol %, andmost preferably greater than 33 mol % and less than 75 mol %, (ii) ahard or crystalline α-olefin polymer (CAOP), in which the α-olefinmonomer (preferably propylene) is present in an amount of from greaterthan 90 up to 100 mol percent, and preferably greater than 93 molpercent, and more preferably greater than 95 mol percent, and mostpreferably greater than 98 mol percent and (iii) a block copolymer,preferably a diblock, having (a) a soft segment and (b) a hard segment,wherein the hard segment of the block copolymer is essentially the samecomposition as the hard polymer in the block composite and the softsegment of the block copolymer is essentially the same composition asthe soft copolymer of the block composite. The block copolymers can belinear or branched. More specifically, when produced in a continuousprocess, the block composites desirably possess PDI from 1.7 to 15,preferably from 1.8 to 3.5, more preferably from 1.8 to 2.2, and mostpreferably from 1.8 to 2.1. When produced in a batch or semi-batchprocess, the block composites desirably possess PDI from 1.0 to 2.9,preferably from 1.3 to 2.5, more preferably from 1.4 to 2.0, and mostpreferably from 1.4 to 1.8. Such block composites are described in, forexample, US Patent Application Publication Nos 2011-0082257,2011-0082258 and 2011-0082249, all published on Apr. 7, 2011 andincorporated herein by reference with respect to descriptions of theblock composites, processes to make them and methods of analyzing them.

The term “crystalline block composite” (CBC) (including the terms“crystalline block copolymer composite”, “crystalline block copolymercomposite resin” and the like) refers to polymers comprising (i) acrystalline ethylene based polymer (CEP), (ii) a crystallinealpha-olefin based polymer (CAOP), and (iii) a block copolymer having(a) a crystalline ethylene block (CEB) and (b) a crystallinealpha-olefin block (CAOB), wherein the CEB of the block copolymer isessentially the same composition as the CEP in the block composite andthe CAOB of the block copolymer is essentially the same composition asthe CAOP of the block composite. Additionally, the compositional splitbetween the amount of CEP and CAOP will be essentially the same as thatbetween the corresponding blocks in the block copolymer. The blockcopolymers can be linear or branched. More specifically, each of therespective block segments can contain long chain branches, but the blockcopolymer segment is substantially linear as opposed to containinggrafted or branched blocks. When produced in a continuous process, thecrystalline block composites desirably possess PDI from 1.7 to 15,preferably 1.8 to 10, preferably from 1.8 to 5, more preferably from 1.8to 3.5. Such crystalline block composites are described in, for example,the following filed patent applications: PCT/US11/41189; U.S. Ser. No.13/165,054; PCT/US11/41191; U.S. Ser. No. 13/165,073; PCT/US11/41194;and U.S. Ser. No. 13/165,096; all filed on 21 Jun. 2011 and incorporatedherein by reference with respect to descriptions of the crystallineblock composites, processes to make them and methods of analyzing them.

CAOB refers to highly crystalline blocks of polymerized alpha olefinunits in which the monomer is present in an amount greater than 90 mol%, preferably greater than 93 mol percent, more preferably greater than95 mol percent, and preferably greater than 96 mol percent. In otherwords, the comonomer content in the CAOBs is less than 10 mol percent,and preferably less than 7 mol percent, and more preferably less than 5mol percent, and most preferably less than 4 mol %. CAOBs with propylenecrystallinity have corresponding melting points that are 80° C. andabove, preferably 100° C. and above, more preferably 115° C. and above,and most preferably 120° C. and above. In some embodiments, the CAOBcomprise all or substantially all propylene units. CEB, on the otherhand, refers to blocks of polymerized ethylene units in which thecomonomer content is 10 mol % or less, preferably between 0 mol % and 10mol %, more preferably between 0 mol % and 7 mol % and most preferablybetween 0 mol % and 5 mol %. Such CEB have corresponding melting pointsthat are preferably 75° C. and above, more preferably 90° C., and 100°C. and above.

“Hard” segments refer to highly crystalline blocks of polymerized unitsin which the monomer is present in an amount greater than 90 molpercent, and preferably greater than 93 mol percent, and more preferablygreater than 95 mol percent, and most preferably greater than 98 molpercent. In other words, the comonomer content in the hard segments ismost preferably less than 2 mol percent, and more preferably less than 5mol percent, and preferably less than 7 mol percent, and less than 10mol percent. In some embodiments, the hard segments comprise all orsubstantially all propylene units. “Soft” segments, on the other hand,refer to amorphous, substantially amorphous or elastomeric blocks ofpolymerized units in which the comonomer content is greater than 10 mol% and less than 90 mol % and preferably greater than 20 mol % and lessthan 80 mol %, and most preferably greater than 33 mol % and less than75 mol %.

The block composite and crystalline block composite polymers arepreferably prepared by a process comprising contacting an additionpolymerizable monomer or mixture of monomers under additionpolymerization conditions with a composition comprising at least oneaddition polymerization catalyst, a cocatalyst and a chain shuttlingagent, said process being characterized by formation of at least some ofthe growing polymer chains under differentiated process conditions intwo or more reactors operating under steady state polymerizationconditions or in two or more zones of a reactor operating under plugflow polymerization conditions. In a preferred embodiment, the blockcomposites of the invention comprise a fraction of block polymer whichpossesses a most probable distribution of block lengths.

Suitable processes useful in producing the block composites andcrystalline block composites may be found, for example, in US PatentApplication Publication No. 2008/0269412, published on Oct. 30, 2008,which is herein incorporated by reference.

When producing a block polymer having a crystalline ethylene block (CEB)and a crystalline alpha-olefin block (CAOB) in two reactors or zones itis possible to produce the CEB in the first reactor or zone and the CAOBin the second reactor or zone or to produce the CAOB in the firstreactor or zone and the CEB in the second reactor or zone. It is moreadvantageous to produce CEB in the first reactor or zone with freshchain shuttling agent added. The presence of increased levels ofethylene in the reactor or zone producing CEB will typically lead tomuch higher molecular weight in that reactor or zone than in the zone orreactor producing CAOB. The fresh chain shuttling agent will reduce theMW of polymer in the reactor or zone producing CEB thus leading tobetter overall balance between the length of the CEB and CAOB segments.

When operating reactors or zones in series it is necessary to maintaindiverse reaction conditions such that one reactor produces CEB and theother reactor produces CAOB. Carryover of ethylene from the firstreactor to the second reactor (in series) or from the second reactorback to the first reactor through a solvent and monomer recycle systemis preferably minimized. There are many possible unit operations toremove this ethylene, but because ethylene is more volatile than higheralpha olefins one simple way is to remove much of the unreacted ethylenethrough a flash step by reducing the pressure of the effluent of thereactor producing CEB and flashing off the ethylene. A more preferableapproach is to avoid additional unit operations and to utilize the muchgreater reactivity of ethylene versus higher alpha olefins such that theconversion of ethylene across the CEB reactor approaches 100%. Theoverall conversion of monomers across the reactors can be controlled bymaintaining the alpha olefin conversion at a high level (90 to 95%).Suitable catalysts and catalyst precursors for use in the presentinvention include metal complexes such as disclosed in WO2005/090426, inparticular, those disclosed starting on page 20, line 30 through page53, line 20, which is herein incorporated by reference. Suitablecatalysts are also disclosed in US 2006/0199930; 2007/0167578;2008/0311812; U.S. Pat. No. 7,355,089 B2; or WO 2009/012215, which areherein incorporated by reference with respect to catalysts.

Preferably, the block composite polymers comprise propylene, 1-butene or4-methyl-1-pentene and one or more comonomers. Preferably, the blockpolymers of the block composites comprise in polymerized form propyleneand ethylene and/or one or more C₄₋₂₀ α-olefin comonomers, and/or one ormore additional copolymerizable comonomers or they comprise4-methyl-1-pentene and ethylene and/or one or more C₄₋₂₀ α-olefincomonomers, or they comprise 1-butene and ethylene, propylene and/or oneor more C₅-C₂₀ α-olefin comonomers and/or one or more additionalcopolymerizable comonomers. Additional suitable comonomers are selectedfrom diolefins, cyclic olefins, and cyclic diolefins, halogenated vinylcompounds, and vinylidene aromatic compounds.

Comonomer content in the resulting block composite polymers may bemeasured using any suitable technique, with techniques based on nuclearmagnetic resonance (NMR) spectroscopy preferred. It is highly desirablethat some or all of the polymer blocks comprise amorphous or relativelyamorphous polymers such as copolymers of propylene, 1-butene or4-methyl-1-pentene and a comonomer, especially random copolymers ofpropylene, 1-butene or 4-methyl-1-pentene with ethylene, and anyremaining polymer blocks (hard segments), if any, predominantly comprisepropylene, 1-butene or 4-methyl-1-pentene in polymerized form.Preferably such segments are highly crystalline or stereospecificpolypropylene, polybutene or poly-4-methyl-1-pentene, especiallyisotactic homopolymers.

Further preferably, the block copolymers of the block composite comprisefrom 10 to 90 weight percent crystalline or relatively hard segments and90 to 10 weight percent amorphous or relatively amorphous segments (softsegments), preferably from 20 to 80 weight percent crystalline orrelatively hard segments and 80 to 20 weight percent amorphous orrelatively amorphous segments (soft segments), most preferably from 30to 70 weight percent crystalline or relatively hard segments and 70 to30 weight percent amorphous or relatively amorphous segments (softsegments). Within the soft segments, the mole percent comonomer mayrange from 10 to 90 mole percent, preferably from 20 to 80 mole percent,and most preferably from 33 to 75 mol % percent. In the case wherein thecomonomer is ethylene, it is preferably present in an amount of 10 mol %to 90 mol %, more preferably from 20 mol % to 80 mol %, and mostpreferably from 33 mol % to 75 mol % percent. Preferably, the copolymerscomprise hard segments that are 90 mol % to 100 mol % propylene. Thehard segments can be greater than 90 mol % preferably greater than 93mol % and more preferably greater than 95 mol % propylene, and mostpreferably greater than 98 mol % propylene. Such hard segments havecorresponding melting points that are 80° C. and above, preferably 100°C. and above, more preferably 115° C. and above, and most preferably120° C. and above.

In some embodiments, the block composites of the invention have a BlockComposite Index (BCI), as defined below, that is greater than zero butless than 0.4 or from 0.1 to 0.3. In other embodiments, BCI is greaterthan 0.4 and up to 1.0. Additionally, the BCI can be in the range offrom 0.4 to 0.7, from 0.5 to 0.7, or from 0.6 to 0.9. In someembodiments, BCI is in the range of from 0.3 to 0.9, from 0.3 to 0.8, orfrom 0.3 to 0.7, from 0.3 to 0.6, from 0.3 to 0.5, or from 0.3 to 0.4.In other embodiments, BCI is in the range of from 0.4 to 1.0, from 0.5to 1.0, or from 0.6 to 1.0, from 0.7 to 1.0, from 0.8 to 1.0, or from0.9 to 1.0.

The block composites preferably have a Tm greater than 100° C.,preferably greater than 120° C., and more preferably greater than 125°C. Preferably the MFR of the block composite is from 0.1 to 1000 dg/min,more preferably from 0.1 to 50 dg/min and more preferably from 0.1 to 30dg/min.

Further preferably, the block composites of this embodiment of theinvention have a weight average molecular weight (Mw) from 10,000 to2,500,000, preferably from 35000 to 1,000,000 and more preferably from50,000 to 300,000, preferably from 50,000 to 200,000.

Preferably, the block composite polymers of the invention compriseethylene, propylene, 1-butene or 4-methyl-1-pentene and optionally oneor more comonomers in polymerized form. Preferably, the block copolymersof the crystalline block composites comprise in polymerized formethylene, propylene, 1-butene, or 4-methyl-1-pentene and optionally oneor more C₄₋₂₀ α-olefin comonomers. Additional suitable comonomers areselected from diolefins, cyclic olefins, and cyclic diolefins,halogenated vinyl compounds, and vinylidene aromatic compounds.

Comonomer content in the resulting block composite polymers may bemeasured using any suitable technique, with techniques based on nuclearmagnetic resonance (NMR) spectroscopy preferred.

Preferably the crystalline block composite polymers of the inventioncomprise from 0.5 to 95 wt % CEP, from 0.5 to 95 wt % CAOP and from 5 to99 wt % block copolymer. More preferably, the crystalline blockcomposite polymers comprise from 0.5 to 79 wt % CEP, from 0.5 to 79 wt %CAOP and from 20 to 99 wt % block copolymer and more preferably from 0.5to 49 wt % CEP, from 0.5 to 49 wt % CAOP and from 50 to 99 wt % blockcopolymer. Weight percents are based on total weight of crystallineblock composite. The sum of the weight percents of CEP, CAOP and blockcopolymer equals 100%.

Preferably, the block copolymers of the invention comprise from 5 to 95weight percent crystalline ethylene blocks (CEB) and 95 to 5 wt percentcrystalline alpha-olefin blocks (CAOB). They may comprise 10 wt % to 90wt % CEB and 90 wt % to 10 wt % CAOB. More preferably, the blockcopolymers comprise 25 to 75 wt % CEB and 75 to 25 wt % CAOB, and evenmore preferably they comprise 30 to 70 wt % CEB and 70 to 30 wt % CAOB.

In some embodiments, the block composites of the invention have aCrystalline Block Composite Index (CBCI), as defined below, that isgreater than zero but less than 0.4 or from 0.1 to 0.3. In otherembodiments, CBCI is greater than 0.4 and up to 1.0. In someembodiments, the CBCI is in the range of from 0.1 to 0.9, from 0.1 to0.8, from 0.1 to 0.7 or from 0.1 to 0.6. Additionally, the CBCI can bein the range of from 0.4 to 0.7, from 0.5 to 0.7, or from 0.6 to 0.9. Insome embodiments, CBCI is in the range of from 0.3 to 0.9, from 0.3 to0.8, or from 0.3 to 0.7, from 0.3 to 0.6, from 0.3 to 0.5, or from 0.3to 0.4. In other embodiments, CBCI is in the range of from 0.4 to 1.0,from 0.5 to 1.0, or from 0.6 to 1.0, from 0.7 to 1.0, from 0.8 to 1.0,or from 0.9 to 1.0.

Further preferably, the crystalline block composites of this embodimentof the invention have a weight average molecular weight (Mw) of 1,000 to2,500,000, preferably of 35000 to 1,000,000 and more preferably of50,000 to 500,000, of 50,000 to 300,000, and preferably from 50,000 to200,000.

The overall composition of each resin is determined as appropriate byDSC, NMR, Gel Permeation Chromatography, Dynamic MechanicalSpectroscopy, and/or Transmission Electron Micrography. Xylenefractionation and high temperature liquid chromatography (“HTLC”)fractionation can be further used to estimate the yield of blockcopolymer, and in particular the block composite index. These aredescribed in more detail in US Patent Application Publication Nos2011-0082257, 2011-0082258 and 2011-0082249, all published on Apr. 7,2011 and incorporated herein by reference with respect to descriptionsof the analysis methods.

For a block composite derived from ethylene and propylene, the insolublefractions will contain an appreciable amount of ethylene that would nototherwise be present if the polymer was simply a blend of iPPhomopolymer and EP copolymer. To account for this “extra ethylene”, amass balance calculation can be performed to estimate a block compositeindex from the amount of xylene insoluble and soluble fractions and theweight % ethylene present in each of the fractions.

A summation of the weight % ethylene from each fraction according toequation 1a results in an overall weight % ethylene (in the polymer).This mass balance equation can also be used to quantify the amount ofeach component in a binary blend or extended to a ternary, orn-component blend.Wt %C ₂ _(Overall) =w _(Insoluble)(wt %C ₂ _(Insoluble) )+w_(soluble)(wt %C ₂ _(soluble) )  Eq. 1a

Applying equations 2a through 4a, the amount of the soft block(providing the source of the extra ethylene) present in the insolublefraction is calculated. By substituting the weight % C₂ of the insolublefraction in the left hand side of equation 2a, the weight % iPP hard andweight % EP soft can be calculated using equations 3a and 4a. Note thatthe weight % of ethylene in the EP soft is set to be equal to the weight% ethylene in the xylene soluble fraction. The weight % ethylene in theiPP block is set to zero or if otherwise known from its DSC meltingpoint or other composition measurement, the value can be put into itsplace.

$\begin{matrix}{{{Wt}\mspace{14mu}\%\mspace{14mu} C_{2_{{Overall}\mspace{14mu}{or}\mspace{14mu}{xylene}\mspace{14mu}{insoluble}}}} = {{w_{iPPHard}\left( {{wt}\mspace{14mu}\%\mspace{14mu} C_{2_{iPP}}} \right)} + {w_{{EP}\mspace{14mu}{soft}}\left( {{wt}\mspace{14mu}\%\mspace{14mu} C_{2_{EPsoft}}} \right)}}} & {{{Eq}.\mspace{14mu} 2}a} \\{w_{{iPPhard}\;} = \frac{{{wt}\mspace{14mu}\%\mspace{14mu} C_{2_{{overall}\mspace{14mu}{or}\mspace{14mu}{xyleneinsoluble}}}} - {{wt}\mspace{14mu}\%\mspace{14mu} C_{2_{EPsoft}}}}{{{wt}\mspace{14mu}\%\mspace{14mu} C_{2_{iPPhard}}} - {{wt}\mspace{14mu}\%\mspace{14mu} C_{2_{EPsoft}}}}} & {{{Eq}.\mspace{14mu} 3}a} \\{\mspace{20mu}{w_{EPsoft} = {1 - w_{iPPHard}}}} & {{{Eq}.\mspace{14mu} 4}a}\end{matrix}$

After accounting for the ‘additional’ ethylene present in the insolublefraction, the only way to have an EP copolymer present in the insolublefraction, the EP polymer chain must be connected to an iPP polymer block(or else it would have been extracted into the xylene soluble fraction).Thus, when the iPP block crystallizes, it prevents the EP block fromsolubilizing.

To estimate the block composite index, the relative amount of each blockmust be taken into account. To approximate this, the ratio between theEP soft and iPP hard is used. The ratio of the EP soft polymer and iPPhard polymer can be calculated using Equation 2a from the mass balanceof the total ethylene measured in the polymer. Alternatively it couldalso be estimated from a mass balance of the monomer and comonomerconsumption during the polymerization. The weight fraction of iPP hardand weight fraction of EP soft is calculated using Equation 2a andassumes the iPP hard contains no ethylene. The weight % ethylene of theEP soft is the amount of ethylene present in the xylene solublefraction.

For example, if an iPP-EP block composite contains an overall ethylenecontent of 47 wt % C₂ and is made under conditions to produce an EP softpolymer with 67 wt % C₂ and an iPP homopolymer containing zero ethylene,the amount of EP soft and iPP hard is 70 wt % and 30 wt %, respectively(as calculated using Equations 3a and 4a). If the percent of EP is 70 wt% and the iPP is 30 wt %, the relative ratio of the EP:iPP blocks couldbe expressed as 2.33:1.

Hence, if one skilled in the art carries out a xylene extraction of thepolymer and recovers 40 wt % insoluble and 60 wt % soluble, this wouldbe an unexpected result and this would lead to the conclusion that afraction of block copolymer was present. If the ethylene content of theinsoluble fraction is subsequently measured to be 25 wt % C₂, Equations2a thru 4a can be solved to account for this additional ethylene andresult in 37.3 wt % EP soft polymer and 62.7 wt % iPP hard polymerpresent in the insoluble fraction.

Since the insoluble fraction contains 37.3 wt % EP copolymer, it shouldbe attached to an additional 16 wt % of iPP polymer based on the EP:iPPblock ratio of 2.33:1. This brings the estimated amount of diblock inthe insoluble fraction to be 53.3 wt %. For the entire polymer(unfractionated), the composition is described as 21.3 wt % iPP-EPDiblock, 18.7 wt % iPP polymer, and 60 wt % EP polymer. The term blockcomposite index (BCI) is herein defined to equal the weight percentageof diblock divided by 100% (i.e. weight fraction). The value of theblock composite index can range from 0 to 1, wherein 1 would be equal to100% diblock and zero would be for a material such as a traditionalblend or random copolymer. For the example described above, the blockcomposite index for the block composite is 0.213. For the insolublefraction, the BCI is 0.533, and for the soluble fraction the BCI isassigned a value of zero.

Depending on the estimations made of the total polymer composition andthe error in the analytical measurements which are used to estimate thecomposition of the hard and soft blocks, between 5 to 10% relative erroris possible in the computed value of the block composite index. Suchestimations include the wt % C2 in the iPP hard block as measured fromthe DSC melting point, NMR analysis, or process conditions; the averagewt % C2 in the soft block as estimated from the composition of thexylene solubles, or by NMR, or by DSC melting point of the soft block(if detected). But overall, the block composite index calculationreasonably accounts for the unexpected amount of ‘additional’ ethylenepresent in the insoluble fraction, the only way to have an EP copolymerpresent in the insoluble fraction, the EP polymer chain must beconnected to an iPP polymer block (or else it would have been extractedinto the xylene soluble fraction).

Crystalline block composites having CAOP and CAOB composed ofcrystalline polypropylene and a CEP and CEB composed of crystallinepolyethylene cannot be fractionated by conventional means. Techniquesbased on solvent or temperature fractionation, for example, using xylenefractionation, solvent/non-solvent separation, temperature risingelution fractionation, or crystallization elution fractionation are notcapable of resolving the block copolymer since the CEB and CAOBcocrystallize with the CEP and CAOP, respectively. However, using amethod such as high temperature liquid chromatography which separatespolymer chains using a combination of a mixed solvent/non-solvent and agraphitic column, crystalline polymer species such as polypropylene andpolyethylene can be separated from each other and from the blockcopolymer.

For crystalline block composites, the amount of isolated PP is less thanif the polymer was a simple blend of iPP homopolymer (in this examplethe CAOP) and polyethylene (in this case the CEP). Consequently, thepolyethylene fraction contains an appreciable amount of propylene thatwould not otherwise be present if the polymer was simply a blend of iPPand polyethylene. To account for this “extra propylene”, a mass balancecalculation can be performed to estimate a crystalline block compositeindex from the amount of the polypropylene and polyethylene fractionsand the weight % propylene present in each of the fractions that areseparated by HTLC. The polymers contained within the crystalline blockcomposite include iPP-PE diblock, unbound iPP, and unbound PE where theindividual PP or PE components can contain a minor amount of ethylene orpropylene respectively.

A summation of the weight % propylene from each component in the polymeraccording to equation 1 results in the overall weight % propylene (ofthe whole polymer). This mass balance equation can be used to quantifythe amount of the iPP and PE present in the diblock copolymer. This massbalance equation can also be used to quantify the amount of iPP and PEin a binary blend or extended to a ternary, or n-component blend. Forthe crystalline block composite, the overall amount of iPP or PE iscontained within the blocks present in the diblock and the unbound iPPand PE polymers.Wt %C3_(Overall) =w _(PP)(wt %C3_(PP))+w _(PE)(wt %C3_(PE))  Eq. 1wherew_(PP)=weight fraction of PP in the polymerw_(PE)=weight fraction of PE in the polymerwt % C3_(PP)=weight percent of propylene in PP component or blockwt % C3_(PE)=weight percent of propylene in PE component or block

Note that the overall weight % of propylene (C3) is preferably measuredfrom C13 NMR or some other composition measurement that represents thetotal amount of C3 present in the whole polymer. The weight % propylenein the iPP block (wt % C3_(PP)) is set to 100 or if otherwise known fromits DSC melting point, NMR measurement, or other composition estimate,that value can be put into its place. Similarly, the weight % propylenein the PE block (wt % C3_(PE)) is set to 100 or if otherwise known fromits DSC melting point, NMR measurement, or other composition estimate,that value can be put into its place.

Based on equation 1, the overall weight fraction of PP present in thepolymer can be calculated using Equation 2 from the mass balance of thetotal C3 measured in the polymer. Alternatively, it could also beestimated from a mass balance of the monomer and comonomer consumptionduring the polymerization. Overall, this represents the amount of PP andPE present in the polymer regardless of whether it is present in theunbound components or in the diblock copolymer. For a conventionalblend, the weight fraction of PP and weight fraction of PE correspondsto the individual amount of PP and PE polymer present. For thecrystalline block composite, it is assumed that the ratio of the weightfraction of PP to PE also corresponds to the average block ratio betweenPP and PE present in this statistical block copolymer.

$\begin{matrix}{w_{PP} = \frac{{{wt}\mspace{14mu}\%\mspace{14mu} C\; 3_{Overall}} - {{wt}\mspace{14mu}\%\mspace{20mu} C\; 3_{PE}}}{{{wt}\mspace{14mu}\%\mspace{14mu} C\; 3_{PP}} - {{wt}\mspace{14mu}\%\mspace{14mu} C\; 3_{PE}}}} & {{Eq}.\mspace{14mu} 2}\end{matrix}$wherew_(PP)=weight fraction of PP present in the whole polymerwt % C3_(PP)=weight percent of propylene in PP component or blockwt % C3_(PE)=weight percent of propylene in PE component or block

Applying equations 3 through 5, the amount of the isolated PP that ismeasured by HTLC analysis is used to determine the amount ofpolypropylene present in the diblock copolymer. The amount isolated orseparated first in the HTLC analysis represents the ‘unbound PP’ and itscomposition is representative of the PP hard block present in thediblock copolymer. By substituting the overall weight % C3 of the wholepolymer in the left hand side of equation 3, and the weight fraction ofPP (isolated from HTLC) and the weight fraction of PE (separated byHTLC) into the right hand side of equation 3, the weight % of C3 in thePE fraction can be calculated using equations 4 and 5. The PE fractionis described as the fraction separated from the unbound PP and containsthe diblock and unbound PE. The composition of the isolated PP isassumed to be the same as the weight % propylene in the iPP block asdescribed previously.wt %C3_(Overall) =w _(PP isolated)(wt %C3_(PP))+w _(PE-fraction)(wt%C3_(PE-fraction))  Eq. 3

$\begin{matrix}{{{wt}\mspace{14mu}\%\mspace{14mu} C\; 3_{{PE}\text{-}{fraction}}} = \frac{{{wt}\mspace{14mu}\%\mspace{14mu} C\; 3_{Overall}} - {w_{PPiolated}\left( {{wt}\mspace{14mu}\%\mspace{14mu} C\; 3_{PP}} \right)}}{w_{{PE}\text{-}{fraction}}}} & {{Eq}.\mspace{14mu} 4} \\{\mspace{20mu}{w_{{PE}\text{-}{fraction}} = {1 - w_{PPisolated}}}} & {{Eq}.\mspace{14mu} 5}\end{matrix}$wherew_(PPisolated)=weight fraction of isolated PP from HTLCw_(PE-fraction)=weight fraction of PE separated from HTLC, containingthe diblock and unbound PEwt % C3_(PP)=weight % of propylene in the PP; which is also the sameamount of propylene present in the PP block and in the unbound PPwt % C3_(PE-fraction)=weight % of propylene in the PE-fraction that wasseparated by HTLCwt % C3_(overall)=overall weight % propylene in the whole polymer

The amount of wt % C3 in the polyethylene fraction from HTLC representsthe amount of propylene present in the block copolymer fraction that isabove the amount present in the ‘unbound polyethylene’.

To account for the ‘additional’ propylene present in the polyethylenefraction, the only way to have PP present in this fraction, is that thePP polymer chain must be connected to a PE polymer chain (or else itwould have been isolated with the PP fraction separated by HTLC). Thus,the PP block remains adsorbed with the PE block until the PE fraction isseparated.

The amount of PP present in the diblock is calculated using Equation 6.

$\begin{matrix}{w_{{PP}\text{-}{diblock}} = \frac{{{wt}\mspace{14mu}\%\mspace{14mu} C\; 3_{{PE}\text{-}{fraction}}} - {{wt}\mspace{14mu}\%\mspace{14mu} C\; 3_{PE}}}{{{wt}\mspace{14mu}\%\mspace{14mu} C\; 3_{PP}} - {{wt}\mspace{14mu}\%\mspace{14mu} C\; 3_{PE}}}} & {{Eq}.\mspace{14mu} 6}\end{matrix}$Wherewt % C3_(PE-fraction)=weight % of propylene in the PE-fraction that wasseparated by HTLC (Equation 4)wt % C3_(PP)=weight % of propylene in the PP component or block (definedpreviously)wt % C3_(PE)=weight % of propylene in the PE component or block (definedpreviously)w_(PP-diblock)=weight fraction of PP in the diblock separated withPE-fraction by HTLC

The amount of the diblock present in this PE fraction can be estimatedby assuming that the ratio of the PP block to PE block is the same asthe overall ratio of PP to PE present in the whole polymer. For example,if the overall ratio of PP to PE is 1:1 in the whole polymer, then itassumed that the ratio of PP to PE in the diblock is also 1:1. Thus theweight fraction of diblock present in the PE fraction would be weightfraction of PP in the diblock (w_(PP-diblock)) multiplied by two.Another way to calculate this is by dividing the weight fraction of PPin the diblock (w_(PP-diblock)) by the weight fraction of PP in thewhole polymer (equation 2).

To further estimate the amount of diblock present in the whole polymer,the estimated amount of diblock in the PE fraction is multiplied by theweight fraction of the PE fraction measured from HTLC.

To estimate the crystalline block composite index, the amount of blockcopolymer is determined by equation 7. To estimate the CBCI, the weightfraction of diblock in the PE fraction calculated using equation 6 isdivided by the overall weight fraction of PP (as calculated in equation2) and then multiplied by the weight fraction of the PE fraction. Thevalue of the CBCI can range from 0 to 1, wherein 1 would be equal to100% diblock and zero would be for a material such as a traditionalblend or random copolymer.

$\begin{matrix}{{CBCI} = {\frac{w_{{PP}\text{-}{diblock}}}{w_{PP}} \cdot w_{{PE}\text{-}{fraction}}}} & {{Eq}.\mspace{14mu} 7}\end{matrix}$Wherew_(PP-diblock)=weight fraction of PP in the diblock separated with thePE-fraction by HTLC (Equation 6)w_(PP)=weight fraction of PP in the polymerw_(PE-fraction)=weight fraction of PE separated from HTLC, containingthe diblock and unbound PE (Equation 5)

For example, if an iPP-PE polymer contains a total of 62.5 wt % C3 andis made under the conditions to produce an PE polymer with 10 wt % C3and an iPP polymer containing 97.5 wt % C3, the weight fractions of PEand PP are 0.400 and 0.600, respectively (as calculated using Equation2). Since the percent of PE is 40.0 wt % and the iPP is 60.0 wt %, therelative ratio of the PE:PP blocks is expressed as 1:1.5.

Hence, if one skilled in the art, carries out an HTLC separation of thepolymer and isolates 28 wt % PP and 72 wt % of the PE fraction, thiswould be an unexpected result and this would lead to the conclusion thata fraction of block copolymer was present. If the C3 content of the PEfraction (wt % C_(3PE-fraction)) is subsequently calculated to be 48.9wt % C3 from equations 4 and 5, the PE fraction containing theadditional propylene has 0.556 wt fraction of PE polymer and 0.444weight fraction of PP polymer (w_(PP-diblock), calculated using Equation6).

Since the PE fraction contains 0.444 weight fraction of PP, it should beattached to an additional 0.293 weight fraction of PE polymer based onthe iPP:PE block ratio of 1.5:1. Thus, the weight fraction of diblockpresent in the PE fraction is 0.741; further calculation of the weightfraction of diblock present in the whole polymer is 0.533. For theentire polymer, the composition is described as 53.3 wt % iPP-PEdiblock, 28 wt % PP polymer, and 18.7 wt % PE polymer. The crystallineblock composite index (CBCI) is the estimated weight fraction of diblockpresent in the whole polymer. For the example described above, the CBCIfor the crystalline block composite is 0.533.

The Crystalline Block Composite Index (CBCI) provides an estimate of thequantity of block copolymer within the crystalline block composite underthe assumption that the ratio of CEB to CAOB within the diblock is thesame as the ratio of crystalline ethylene to crystalline alpha-olefin inthe overall crystalline block composite. This assumption is valid forthese statistical olefin block copolymers based on the understanding ofthe individual catalyst kinetics and the polymerization mechanism forthe formation of the diblocks via chain shuttling catalysis as describedin the specification.

The calculation of CBCI is based on the analytical observation that theamount of free CAOP is lower than the total amount of CAOP that wasproduced in the polymerization. The remainder of the CAOP is bound toCEB to form the diblock copolymer. Because the PE fraction separated byHTLC contains both the CEP and the diblock polymer, the observed amountof propylene for this fraction is above that of the CEP. This differencecan be used to calculate the CBCI.

Based solely on the analytical observations without prior knowledge ofthe polymerization statistics, the minimum and maximum quantities ofblock copolymer present in a polymer can be calculated, thusdistinguishing a crystalline block composite from a simple copolymer orcopolymer blend.

The upper bound on the amount of block copolymer present within acrystalline block composite, w_(DB) _(Max) , is obtained by subtractingthe fraction of unbound PP measured by HTLC from one as in Equation 8.This maximum assumes that the PE fraction from HTLC is entirely diblockand that all crystalline ethylene is bound to crystalline PP with nounbound PE. The only material in the CBC that is not diblock is thatportion of PP separated via HTLC.w _(DB) _(Max) =1−w _(PP) _(isolated)   Eq. 8

The lower bound on the amount of block copolymer present within acrystalline block composite, w_(DB) _(Min) , corresponds to thesituation where little to no PE is bound to PP. This lower limit isobtained by subtracting the amount of unbound PP as measured by HTLCfrom the total amount of PP in the sample as shown in Equation 9.w _(DB) _(Min) =w _(PP) −w _(PP) _(isolated)   Eq. 9

Furthermore, the crystalline block composite index will fall betweenthese two values: w_(DB) _(Min) <CBCI≤w_(DB) _(Max) .

Based on the polymerization mechanism for production of the crystallineblock composites, the CBCI represents the best estimate of the actualfraction of diblock copolymer in the composite. For unknown polymersamples, w_(DB) _(min) can be used to determine if a material is acrystalline block composite. For a physical blend of PE and PP, theoverall weight fraction of PP should be equal to that of the wt % PPfrom HTLC and the lower bound on diblock content, Equation 9, is zero.If this analysis is applied to a sample of PP that does not contain PEboth the weight fraction of PP and amount of PP obtained from HTLC are100% and again the lower bound on diblock content, Equation 9, is zero.Finally if this analysis is applied to a sample of PE that does notcontain PP then both the weight fraction of PP and weight fraction PPrecovered via HTLC are zero and the lower bound on diblock, Equation 9,is zero. Because the lower bound on diblock content is not greater thanzero in any of these three cases, these materials are not crystallineblock composites.

Differential Scanning calorimetry (DSC) is used to measure, among otherthings, the heats of fusion of the crystalline block and blockcomposites and is performed on a TA Instruments Q1000 DSC equipped withan RCS cooling accessory and an auto sampler. A nitrogen purge gas flowof 50 ml/min is used. The sample is pressed into a thin film and meltedin the press at about 190° C. and then air-cooled to room temperature(25° C.). About 3-10 mg of material is then cut, accurately weighed, andplaced in a light aluminum pan (ca 50 mg) which is later crimped shut.The thermal behavior of the sample is investigated with the followingtemperature profile: the sample is rapidly heated to 190° C. and heldisothermal for 3 minutes in order to remove any previous thermalhistory. The sample is then cooled to −90° C. at 10° C./min cooling rateand held at −90° C. for 3 minutes. The sample is then heated to 190° C.at 10° C./min heating rate. The cooling and second heating curves arerecorded. For the heat of fusion measurements for the CBC and BC resins,as known and routinely performed by skilled practitioners in this area,the baseline for the calculation is drawn from the flat initial sectionprior to the onset of melting (typically in the range of from about −10to about 20° C. for these types of materials) and extends to the end ofmelting for the second heating curve.

The Layer B BC and/or CBC resin(s) can collectively be summarized ascomprising:

-   -   i) an ethylene polymer (EP) comprising from 10 to 100 mol %        polymerized ethylene;    -   ii) an alpha-olefin-based crystalline polymer (CAOP); and    -   iii) a block copolymer comprising (a) an ethylene polymer block        (EB) comprising from 10 to 100 mol % ethylene and (b) a        crystalline alpha-olefin block (CAOB).

In general, BC's that can be used in Layer B according to the presentinvention will have heat of fusion values (generally related to theirethylene content in the EP and EB) of at least 20 Joules per gram (J/g),more preferably at least 25 J/g, still more preferably at least 30 J/gand most preferably at least 35 J/g, as measured by DSC. In general,CBC's that can be used in Layer B according to the present inventionwill have heat of fusion values (reflecting the relatively higherethylene content in the CEP and CEB) as measured by DSC of at least 85Joules per gram (J/g), more preferably at least 90 J/g. In either case,the heat of fusion values for polymers of these types would generallyhave a maximum in the area of 125 J/g. For the heat of fusionmeasurements, as generally known and performed by practitioners in thisarea, the DSC is run as generally described below under nitrogen at 10°C./min from 23° C. to 220° C., held isothermal at 220° C., dropped to23° C. at 10° C./min and ramped back to 220° C. at 10° C./min. Thesecond heat data is used to calculate the heat of fusion of the meltingtransition.

In a preferred embodiment the Layer B comprises a BC. Preferred are BC'swherein the component (iii)(a) EB comprises greater than 40 mol %,preferably greater than 60 mol %, more preferably greater than 70 mol %,more preferably greater than 74 mol %, and most preferably greater than85 mol percent of polymerized ethylene, the balance being preferablypolymerized propylene. Preferred BC's have a block composite index (BCI)of at least 0.1, preferably at least 0.3, more preferably at least 0.5;more preferably at least 0.7 more preferably at least 0.9. PreferredBC's generally have a MFR of at least 1, preferably at least 2,preferably at least 3 and up to and including preferably 50, morepreferably 40, and most preferably up to and including 30 dg/min. Ifemploying a blend comprising a BC in Layer B of a film according to theinvention, preferred blends comprise at least 40 wt % BC based on theweight of the blend, preferably at least 60 wt %, preferably at least 75wt %, and more preferably at least 80 wt % block composite in a blendfor use in the B layer.

In another preferred embodiment the B layer comprises a CBC. PreferredCBC's comprise in the component (iii) CEB greater than 90 mol %polymerized ethylene, more preferably greater than 93 mol %, and mostpreferably greater than 95 mol percent of polymerized ethylene.Preferred CBC's have a crystalline block composite index (CBCI) of atleast 0.3; preferably at least 0.5; preferably at least 0.7; and morepreferably at least 0.9. Preferred CBC's generally have a MFR of atleast 1 dg/min, preferably at least 2, and preferably at least 3 dg/minup to and including 50 dg/min, more preferably 40, more preferably 30dg/min. If employing a blend comprising a CBC in Layer B of a filmaccording to the invention, preferred blends comprise at least 40 wt %,more preferably 60 wt %, more preferably 75 wt %, and more preferably 80wt % CBC in a blend for use in the B layer.

Preferred BC and/or CBC resin(s) for Layer B have a CAOB amount (in part(iii)) in the range of from 30 to 70 weight % (based on (iii)),preferably at least 40 wt %, more preferably at least 45 wt % based on(iii), and preferably up to 60 wt %, more preferably up to 55 wt % andmost preferably of 50 wt % based on (iii), the balance in each casebeing ethylene polymer block.

Blends of these CBC and BC types of resins can also be used in the LayerB as (a) a blend with an amount of one or more different resin of thesame type, (b) a blend with an amount of one or more resin of the othertype or (c) a blend of a BC, a CBC or an (a) or (b) blend with one ormore other polymers, including polyolefins as described herein. Suitableadditional components could be, for example, LLDPE, LDPE, an impactmodifier such as ethylene octene copolymer plastomers such as AFFINITYPL 1880G, PL8100G, and PL 1850G, ethylene octene copolymer elastomerssuch as ENGAGE 8842, ENGAGE 8150, and ENGAGE XLT 8677, or olefin blockcopolymers such as for example INFUSE 9100 and 9107 brand polymer orpropylene based elastomers such as VERSIFY 2300 and VERSIFY 3300 brandresins available from The Dow Chemical Company. In alternativeembodiments, the CBC and/or BC polymer resins of Layer B can be blendedwith other polyolefin resins that are grafted or functionalized withglycidyl methacrylate, maleic anhydride (MAH), amines or silane or theycan be blended with polar copolymers of ethylene such as EEA, EVA, EMA,EnBA, EAA and the like. If used, the additional blend polymer needs tobe (i) miscible or compatible with the BC or CBC, (ii) have little, ifany, deleterious impact on the desirable properties of the BC or CBC,e.g., optics and low modulus, and (iii) used in amounts such that thepolyolefin BC or CBC constitutes at least 50, preferably at least 70 andmore preferably at least 80, weight percent of the blend. If used, blendcomponents would be used in Layer B resins in amounts at least of 2weight percent, preferably at least 5 and more preferably at least 8weight percent and preferably less than 30 weight percent, preferablyless than 25 weight percent and more preferably less than 20 weightpercent. Blending can be used to provide improved compatibility(adhesion) with C and/or higher polarity A layers under a range ofconditions and lower costs. In particular, blends (or sub-layers asdescribed below) would desirably be employed where Layer B is employedwith additives and/or stabilizers such as colorants, UV and antioxidantstabilizers or with polar copolymers of ethylene. Blends can also beadvantageously employed where this film surface needs reflectance and/orweathering properties.

In an alternative embodiment of the present invention, all or part ofthe BC and/or CBC component in the Layer B are grafted or functionalizedwith glycidyl methacrylate, maleic anhydride (MAH), amines or silane toprovide desired property modifications such as improved adhesion toother films or the surfaces of articles. In general, functionalizationor grafting can be done by techniques known to those skilled in this artarea. Particularly useful and applicable techniques are taught in UnitedStates patent applications filed Dec. 14, 2011: (a) Ser. No. 61/570,464entitled, “FUNCTIONALIZED BLOCK COMPOSITE AND CRYSTALLINE BLOCKCOMPOSITE COMPOSITIONS AS COMPATIBILIZERS and (b) Ser. No. 61/570,340entitled, “FUNCTIONALIZED BLOCK COMPOSITE AND CRYSTALLINE BLOCKCOMPOSITE COMPOSITIONS”, which are incorporated herein by reference.

In another embodiment resin(s) employed in Layer B may contain curing orcrosslinking additives or be cured or crosslinked by other means. Thecuring or crosslinking is typically performed at the time of assemblingthe multilayer film into a laminate structure or module or after,usually shortly after. Crosslinking can be affected by any one of anumber of different and known methods, e.g., by the use of thermallyactivated free radical initiator additives, e.g., peroxides and azocompounds; by the use of photoinitiators, e.g., benzophenone; by the useof radiation techniques including electron-beam and x-ray; or by the useof vinyl silane, e.g., vinyl tri-ethoxy or vinyl tri-methoxy silane witha moisture cure.

In another embodiment, the B layer can comprise two or more layers(sub-layers) where each of the sub-layers may comprise differingcompositions such as differing BC's, CBC's or blends. Multiplesub-layers are advantageously employed in the Layer B to provide variousadvantages, such as improved adhesion between Layer C and Layer A. Inparticular, A and C layers that are particularly dissimilar anddifficult to adhere to each other can be adhered better and morestrongly by using differing, gradient blends of polar ethylenecopolymer(s) with CBC or BC in sub-layers within the B layer. In thisway, the polar ethylene copolymer/CBC or BC blends in the adjacent,contacting layers progress through a gradient of blend ratios that aremiscible or highly compatible with the immediately adjacent layer andtransition from a composition suited to adhere well to one (but not theother) of the A or C layers and transition to a composition suited toadhere well to the other of the A or C layers. For example, thesub-layering in Layer B could comprise layers, B1 through B4: layer B1of CBC/10% VA EVA, layer B2 of CBC/18% VA-EVA, layer B3 of CBC/24%VA-EVA; and layer B4 of 30% VA-EVA to adhere a polypropylene Layer C toan encapsulant Layer A of EVA (30% VA).

Encapsulation Layer A Polyolefin Resin Components

Layer A in the films according to the invention is replacing a rear“encapsulation film layer” that is typically a separate film that isneeding to be assembled into the layered electronic device. In thevarious types of electronic device and PV module structures these layersare sometimes referred to in as “encapsulation” films or layers or“protective” films or layers or “adhesive” films or layers where thesame or similar film is used on both sides of the electronic device orPV cell and “sandwiches” it. Typically, these layers function toencapsulate and protect the interior photovoltaic cell from moisture andother types of physical damage and adhere to other layers, such as aglass or other top sheet material. Using the same or similar compositionfilm for both sides obtains optimum adhesion and compatibility betweensuch layers. For the front side of the electronic device or PV cell,sufficient light transmission is needed, but in the integratedbacksheet, light transmission of the Layer A is less important althoughsufficient transmission is desirable for increasing reflection of lightthat passes through the PV module and reflects off one or more of thesurface layers of the integrated backsheet. According to the presentinvention, therefore, the top encapsulation layer of the integratedbacksheet can employ the same or different resin(s) as used in a frontencapsulation film. Relative to the front encapsulation films that areused with the top encapsulation layer of the integrated backsheetsaccording the present invention, optical clarity is not as important.However, in most other respects, the top encapsulation Layer A of theintegrated backsheet according to the present invention will require thesame performance and can be prepared from the same or similarcompositions as the known front encapsulation films. As is known, goodphysical, electrical (such as resistivity, dielectric breakdownstrength, and partial discharge), and moisture resistance properties,moldability, adhesion to adjacent PV components and low cost are amongthe desirable qualities.

Film compositions suitable for use as the top encapsulation layers ofthe integrated backsheets according the present invention include thoseused and in the same manner and amounts as the light transmitting layersused in the known PV module laminate structures, e.g., such as thosetaught in U.S. Pat. No. 6,586,271, US Patent Application PublicationUS2001/0045229 A1, WO 99/05206 and WO 99/04971; all of which areincorporated herein by reference.

In general, the top encapsulating layers can include one or more of thedifferent types of polymer materials discussed below and/or otherwiseknown or used for encapsulation layers and assembled into encapsulationfilm or layer formulations. These can be very generally summarized intoseveral groups of A layers as follows:

A1—Layers comprising polyolefin based resins using silane grafting andcontaining UV stabilizers.

A2—Layer comprising polar ethylene copolymer resins such as EVA, EEA,EnBA, EMA or blends, including with silane grafting and UV stabilizers.See for example EP 2 056 356 A1 and EP 2 056 356 A1.

A3—Poly(vinyl butyral) resins, e.g., PVB. See US2008/0210287A1.

Multilayer structures comprising at least a surface (cell contacting)layer of one of A1 through A3 layers with layers of various otherethylene polymer or copolymer resins for optimizing reflectance,adhesion or economics such as sub-layers with different densities;sub-layers with differing silane levels; sub-layers of differing typesof above resins; and sub-layers having different functionality orpurpose, such as reflecting layers.

A1—Layers Comprising Olefinic Polymers and Interpolymers of Ethylene—

Some specific examples of A1 olefinic polymers and interpolymers usefulin this invention, particularly in the top layer of the backsheet,include very low density polyethylene (VLDPE) (e.g., FLEXOMER®ethylene/1-hexene polyethylene made by The Dow Chemical Company),homogeneously branched, linear ethylene/α-olefin copolymers (e.g.TAFMER® by Mitsui Petrochemicals Company Limited and EXACT® by ExxonChemical Company), homogeneously branched, substantially linearethylene/α-olefin polymers (e.g., AFFINITY® and ENGAGE® polyethyleneavailable from The Dow Chemical Company), ethylene multi-blockcopolymers (e.g., INFUSE® olefin block copolymers available from The DowChemical Company), linear ethylene-based polymers such as ATTANE™ UltraLow Density Linear Polyethylene Copolymer, linear ethylene-basedpolymers such as DOWLEX™ Polyethylene Resins, ELITE™ brand enhancedpolyethylene resin, all available from The Dow Chemical Company. Themore preferred polyolefin copolymers for use in the top layer of thebacksheet are the homogeneously branched linear and substantially linearethylene copolymers, particularly the substantially linear ethylenecopolymers which are more fully described in U.S. Pat. Nos. 5,272,236,5,278,272 and 5,986,028, and the ethylene multi-block copolymers whichare more fully described in U.S. Pat. No. 7,355,089, WO 2005/090427,US2006/0199931, 2006/0199930, 2006/0199914, 2006/0199912, 2006/0199911,2006/0199910, 2006/0199908, 2006/0199906, 2006/0199905, 2006/0199897,2006/0199896, 2006/0199887, 2006/0199884, 2006/0199872, 2006/0199744,2006/0199030, 2006/0199006 and 2006/0199983.

As known, for providing crosslinking and initiating grafting, theseolefinic polymers and interpolymers can have desired weight percentagelevels (based on polymer resin) of known peroxides (such as Luperox101)—at least 0.01, preferably at least 0.025, more preferably at least0.05 weight percent and up to and including 0.5, preferably less than orequal to 0.25 weight percent.

As known, for providing improved adhesion, these olefinic polymers andinterpolymers can have desired weight percentage levels (based onpolymer resin) of known silanes (such as VTMS) added during an extrusionstep—at least 0.25, preferably 0.4, preferably 0.5 weight percent up toand including 2.0 wt %, preferably 1.8, preferably 1.65, preferably 1.5weight percent. They can also contain standard UV stabilizers andantioxidants such as listed herein in amounts of up to 3%.

A2—Encapsulants Comprising Polar Ethylene Copolymers

In another embodiment, polar ethylene copolymers can be used as topencapsulant layers (A) of the integrated backsheet. Typical copolymersthat could be used are ethylene vinyl acetate (EVA), ethylene ethylacrylate (EEA), ethylene methacrylate (EMA) and ethylene n-butylacrylate (EnBA). Other similar known copolymers could be used as well.Typically, these copolymers have a silane grafted such as VTMS wheresilane levels (in weight percent based on polymer resin) are typicallyat least 0.25, preferably 0.4, preferably 0.5 weight percent up to andincluding 2.0 wt %, preferably 1.8, preferably 1.65, and preferably 1.5weight percent. These resins also typically include optional stabilizersadditives as listed below, if used, in amounts of at least 0.01 wt %,preferably 0.02 and up to and including 3 wt %, preferably 2, andpreferably 1 wt %. Some copolymers may also have additional functionalgroups added such as, for example, alkyleneoxy groups and the like asdisclosed in, for example, EP 2056356 A1. These copolymers typicallyhave a melt index (MI as measured by the procedure of ASTM D-1238 (190C/2.16 kg)) of less than 100, preferably 75, more preferably 50 and evenmore preferably 30, g/10 min. The typical minimum MI is at least 0.3,preferably 0.7 and even more preferably 1 g/10 min.

One particularly preferred polyolefin for use in the top layer of theintegrated backsheet is an EVA copolymer that will form a sealingrelationship with the electronic device and/or another component of themodule, e.g., encapsulant, a glass cover sheet, etc. when brought intoadhesive contact with the device or other component. EVA copolymers aregenerally characterized as semi-crystalline, flexible and having goodoptical properties, e.g., high transmission of visible and UV-light andlow haze. The ratio of units derived from ethylene to units derived fromvinyl acetate in the copolymer, before grafting or other modification,can vary widely, but typically the EVA copolymer contains at least 20,preferably at least 24, more preferably at least 26 and even morepreferably at least 28, wt % units derived from vinyl acetate.Typically, the EVA copolymer contains less than 35, preferably less than34, and more preferably less than 33 wt % units derived from vinylacetate. The EVA copolymer can be made by any process includingemulsion, solution and high-pressure polymerization.

In another embodiment, possible encapsulant layers comprise blends of A1and A2 with each other and/or with different polyolefins such asdiffering densities, MI or type.

A3—Poly(Vinyl Butyral) Resins

Poly (vinyl butyral) resins could also be used as the encapsulant in theintegrated backsheet such as disclosed in US2008/0210287A1.

A4—Multilayers of Various Encapsulants

In another embodiment, the top encapsulant Layer A can comprise one ormore layers of encapsulants described above to provide optimumreflectance, adhesion or economics. Layers can have differentencapsulant resins composition, densities, silane levels, orfunctionality or purpose. For example one of the many encapsulant layerscould be a primary reflecting layer. However, it is preferred thatadjacent layers have good interlayer adhesion.

Layer A and B Crosslinking

Due to the low density and modulus of at least some of the topencapsulant Layer A resins and Layer B used in the practice of thisinvention, these polymers can be cured or crosslinked at the time of orafter, usually shortly after, construction of a laminated device such asan ED a PV module. Crosslinking can be affected by any one of a numberof different and known methods, e.g., by the use of thermally activatedinitiators, e.g., peroxides and azo compounds; photoinitiators, e.g.,benzophenone; radiation techniques including E-beam and x-ray; vinylsilane, e.g., vinyl tri-ethoxy or vinyl tri-methoxy silane; and moisturecure.

Additives

The individual layers of the multilayered structure can further compriseone or more additives. Exemplary additives include UV-stabilizers,UV-absorbers, and antioxidants. These additives and stabilizers areuseful in, e.g., reducing the oxidative degradation and improving theweatherability of the product. Suitable stabilizers include hinderedamine light stabilizers and benzoates, including combinations of these,such as Cynergy A400, A430, and R350, Cyasorb UV-3529, Cyasorb UV-3346,Cyasorb UV-3583 Hostavin N30, Univil 4050, Univin 5050, ChimassorbUV-119, Chimassorb 944 LD, Tinuvin 622 LD and the like; UV absorberssuch as benzophenones, benzotriazoles or triazines, including examplesof these such as Tinuvin 328 or Cyasorb UV-1164 and the like and;primary and secondary antioxidants such as Cyanox 2777, Irganox 1010,Irganox 1076, Irganox B215, Irganox B225, PEPQ, Weston 399, TNPP,Irgafos 168 and Doverphos 9228. The amounts of stabilizers needed dependon the type, aging environment and longevity desired and are used in themanner and, as is commonly known in the art, the amounts typically rangebetween greater than 0.01 and less than 3% weight percent based on thepolymer weight being stabilized.

Other additives that can be used include, but are not limited to slipadditives such as erucamde and stearamide and the like, polymer processaids such as Dyneon fluropolymer elastomers like Dynamar FX5930,pigments and fillers such as DuPont TiO2 products numbered R960, R350,R105, R108, or R104, and carbon blacks such as used in Dow DNFA-0037masterbatch or provided by Cabot. These and other potential additivesare used in the manner and amount as is commonly known in the art.

Multilayer Film Structures and ED Modules

In describing the use of the polymer components above to make laminateor layered structures, there are a number of terms that are regularlyused and defined as follows.

“Layer” means a single thickness, coating or stratum continuously ordiscontinuously spread out or covering a surface.

“Multi-layer” means at least two layers.

“Facial surface”, “planar surface” and like terms as related to films orlayers mean the surfaces of the layers that are in contact with theopposite and adjacent surfaces of the adjoining layers. Facial surfacesare in distinction to edge surfaces. A rectangular film or layercomprises two facial surfaces and four edge surfaces. A circular layercomprises two facial surfaces and one continuous edge surface.

“In adhering contact” and like terms mean that one facial surface of onelayer and one facial surface of another layer are in touching andbinding contact to one another such that one layer cannot be removed forthe other layer without damage to the in-contact facial surfaces of bothlayers.

“Sealing relationship” and like terms mean that two or more components,e.g., two polymer layers, or a polymer layer and an electronic device,or a polymer layer and a glass cover sheet, etc., join with one anotherin such a manner, e.g., co-extrusion, lamination, coating, etc., thatthe interface formed by their joining is separated from their immediateexternal environment.

The polymeric materials as discussed above can be used in this inventionto construct multilayer structure film or sheet, which is used in turnto construct electronic device modules in the same manner and using thesame amounts as is known in the art, e.g., such as those taught in U.S.Pat. No. 6,586,271, US Patent Application Publication US2001/0045229 A1,WO 99/05206 and WO 99/04971. As discussed above, the films according tothe invention can be used to construct the protective “skins” forelectronic device modules or assemblies, i.e., multilayered structurescomprising an electronic device. As well these films can also serve asthe back encapsulant layer of such devices. They are particularly suitedfor application to the back or rear facing surface of such devices as acombined encapsulant with backsheet, i.e., “integrated backsheet”.Preferably these multilayered structures, e.g., integrated backsheets,are co-extruded, i.e., all layers of the multilayered structures areextruded at the same time, such that as the multilayered structure isformed.

Depending upon their intended use, the multilayer film or sheetstructures according to the present invention have certain physicalproperty and other performance requirements in the areas of toughness,reflectance, tensile strength, heat resistance, dimensional stability,electrical properties (such as resistivity, dielectric breakdownstrength, and partial discharge), and weatherability. The structure mustalso sufficiently adhere to the appropriate surface of the ED activeelement, any metal leads and a front encapsulant film. In the filmsaccording to the present invention, the layer materials as describedabove are provided into film layers generally as follows:

Layer C—Comprising High Melting Point Polyolefin Resins

In general, Layer C in the multilayer backsheet structures according tothe present invention is prepared from the “Layer C High Melting PointPolyolefin Resins” as discussed above. In one preferred embodiment, itis preferably a highly crystalline homopolymer polypropylene resin.Depending upon the specific performance requirements for the film and/ora module structure in which it is intended for use, the thickness ofLayer C is typically in the range of from 100 μm to 375 μm. As forminimum thickness, Layer C is preferably at least 100 μm, morepreferably at least 150 μm, more preferably at least 160 μm and mostpreferably at least 170 μm thick. As for maximum thickness, thethickness of Layer C can be up to and including 375 μm, preferably 300μm, more preferably 275 μm and most preferably 250 μm.

Encapsulating Top Layer A

As mentioned above, the top layer of the multilayered films according tothe present invention can utilize the known different types ofencapsulating film formulations sometimes referred to in various typesof PV module structures as “encapsulation” films or layers or“protective” films or layers or “adhesive” films or layers. As is known,nature and thickness of this layer are somewhat determined by thespecific performance requirements of the electronic device and/or finalmodule structure, including the matching front encapsulation film layerfilm. In general, the thickness of Layer A is typically in the range offrom 0.15 to 1.25 mm. As for minimum thickness, Layer A is as thick asneeded to provide, along with the front encapsulation film, theprotection needed in the electronic device module, but is preferably atleast 0.20 mm, more preferably at least 0.25 and most preferably atleast 0.30 mm thick. As for maximum thickness, the thickness and cost ofLayer A are desirably minimized but can be up to and including 1.25 mm,preferably 0.875 mm, more preferably 0.625 mm and most preferably 0.500mm.

In a preferred embodiment of the present invention, the A Layer is ofthe type A1 described above. An example of a formulation of such a layerwould be ENGAGE elastomer blend that is silane grafted and contains UVand AO stabilizers.

Layer B—Tie Layer Comprising Block Composite Resin

In general, Layer B in the multilayer backsheet film structuresaccording to the several embodiments of the present invention isprepared from the “Layer B Block Composite Resins” as discussed above.In one preferred embodiment, it is preferably a crystalline blockcopolymer composite resin. Depending upon the specific performancerequirements for the film and/or a module structure in which it isintended for use, the thickness of Layer B is typically in the range offrom 10 μm to 150 μm. As for minimum thickness, Layer B is only as thickas needed to tie the adjacent Layers A and C together and is preferablyat least 15 μm, more preferably at least 20 μm and most preferably atleast 25 μm thick. As for maximum thickness, the thickness and cost ofLayer B are desirably minimized but can preferably be up to andincluding 125 μm, more preferably 100 μm and most preferably 75 μmthick.

The multilayer films according to the present invention, depending uponthe desired structure of the laminate structure in which they areemployed, comprise Layer B in adhering contact with the bottom Layer Cand in adhering contact with top layer A. The composition of the Layer Bcan be selected and optimized along the lines discussed herein dependingupon the intended film structure and usage of the film structure.

There are a number of desirable features and advantages realized inutilizing these integrated backsheets of the present invention toprepare electronic device modules such as PV modules. The structuresaccording to the present invention provide the necessary highresistivity and excellent level of dielectric protection needed foroperations of the electronic devices, such as current conductance forphotovoltaic cells. Otherwise, the other materials typically employed,such as laminated encapsulant and separate backsheet sometimes performedpoorly in this aspect (see Schott Backsheet article in Special Editionof PV Magazine dated June 2010 (www.pv-magazine.com)). As known, whenusing a separate rear encapsulation film in assembling an electronicdevice module, shrinkage and wrinkling of the separate laminatedencapsulation layer in those situations can be particularly severe andespecially detrimental to the precise location and connected leads ofthe electronic device, not to mention physically damaging to the fragiledevices themselves, e.g., a PV cell. Instead, according to the presentinvention, when an encapsulation Layer A is laminated and fixed to thehigher melting point Layer C, preferably during a coextrusion process,prior to use in any electronic device assembly lamination process, theencapsulation layer is not free to undergo free shrinkage therebyreducing or eliminating problems otherwise encountered during laminationof the separate encapsulation layer. When the integrated backsheetencapsulation layer is initially fixed to the front encapsulation filmin the lamination process, it thereby reduces the front encapsulationfilm shrinkage, as well. In general, the process of handling andassembling electronic based devices can be greatly improved.

With the use of the integrated backsheet structures according to thepresent invention, the back sheet and encapsulation layers can easily beused to provide optimized optical properties in the electronic devicemodules, such as light reflectance that is beneficial in PV modulestructures. Also, entrapment of detrimental air bubbles and/or otherimpurities and between back sheet and encapsulation film are alsoavoided when the encapsulation layer is located as a coextruded layeronto the integrated backsheet structure according to the presentinvention. Otherwise, there is a need to remove air between layersduring the heat/pressure lamination process requiring the encapsulantoften to be embossed on both sides resulting in tacking and buildup ofmaterial on emboss rolls during manufacture. In addition, it is knownthat typical encapsulating films are often tacky and difficult tohandle, requiring handling with a separating, protective paper layer.According to present invention, it is possible to handle and employ theintegrated backsheet without supporting protective paper layers that addunnecessary costs and waste. In general, it can be seen that integratedbacksheets according to the present invention save time and cost thatare otherwise needed to handle the separate encapsulation film componentof the PV modules.

In all cases, the top facial surface of the top A Layer of themultilayered structure exhibits good adhesion for the facial surfaces ofeither the electronic device, particularly the back surface of thedevice, or the encapsulation layer material that encapsulates thedevice.

Depending somewhat upon the specific structure and process for utilizingthe film structures according to the present invention, such filmstructures can be prepared by any of a large number of known filmproduction processes including but not limited to extrusion orco-extrusion methods such as blown-film, modified blown-film,calendaring and casting. There are many known techniques which can beemployed for providing multilayer films (up to and including microlayerfilms), including for example in U.S. Pat. Nos. 5,094,788; 5,094,793;WO/2010/096608; WO 2008/008875; U.S. Pat. Nos. 3,565,985; 3,557,265;3,884,606; 4,842,791 and 6,685,872 all of which are hereby incorporatedby reference herein.

Integrated Backsheet Structure and Thickness

The overall thickness of the multilayered integrated backsheetstructures according to the present invention, prior to lamination intoelectronic devices and/or anything else, is typically between 0.2 and1.5 mm (8 to 60 mils). Preferably to provide sufficient physicalproperties and performance, the integrated backsheet thickness is atleast 0.25 mm (10 mils), and more preferably at least 0.4 mm (16 mils).To maintain light weight and low costs the integrated backsheetthickness is preferably 1.05 mm (42 mils) or less, more preferably 0.95mm (38 mils) or less. This includes any optional, additional layers thatform and are an integral part of the multilayer structure.

FIG. 1, not to scale, is a cross-sectional view of an electronic devicecomprising a three-layer backsheet 14 comprising “A” Layer 14A, “B”Layer 14B and “C” Layer 14C all in adhering contact with each other,further in adhering contact with a front encapsulant film 12 and theback surface of an electronic device, e.g., a PV cell.

PV Module Structures and Terms

“Photovoltaic cells” (“PV cells”) contain one or more photovoltaiceffect materials of any of several inorganic or organic types which areknown in the art and from prior art photovoltaic module teachings. Forexample, commonly used photovoltaic effect materials include one or moreof the known photovoltaic effect materials including but not limited tocrystalline silicon, polycrystalline silicon, amorphous silicon, copperindium gallium (di)selenide (CIGS), copper indium selenide (CIS),cadmium telluride, gallium arsenide, dye-sensitized materials, andorganic solar cell materials.

As shown by the diagram of a PV module in FIG. 1, PV cells (11) aretypically employed in a laminate structure and have at least onelight-reactive surface that converts the incident light into electriccurrent. Photovoltaic cells are well known to practitioners in thisfield and are generally packaged into photovoltaic modules that protectthe cell(s) and permit their usage in their various applicationenvironments, typically in outdoor applications. As used herein, PVcells may be flexible or rigid in nature and include the photovoltaiceffect materials and any protective coating surface materials that areapplied in their production as well as appropriate wiring and electronicdriving circuitry (not shown).

“Photovoltaic modules” (“PV Modules”), such as represented by theexample structure shown in FIG. 1, contain at least one photovoltaiccell 11 (in this case having a single light-reactive or effectivesurface directed or facing upward in the direction of the top of thepage) surrounded or encapsulated by a light transmitting protectiveencapsulating sub-component 12 on the top or front surface and anprotective encapsulating layer 14A of integrated backsheet 14 on therear or back surface. Combined, 12 and 14A form a combination of twoencapsulating layers “sandwiching” the cell. The light transmittingcover sheet 13 has an interior surface in adhering contact with a frontfacial surface of the encapsulating film layer 12, which layer 12 is, inturn, disposed over and in adhering contact with PV cell 11.

Multilayer backsheet films according to the present invention 14 act asa substrate and supports a rear surface of the PV cell 11. Integratedbacksheet layer 14 need not be light transmitting if the surface of thePV cell to which it is opposed is not effective, i.e., reactive tosunlight.

In the case of a flexible PV module, as the description “flexible”implies, it would comprise a flexible thin film photovoltaic cell 11.Such a structure comprises the top layer or cover sheet 13 covering andadhered to a front facial surface of a light transmitting encapsulatingfilm layer 12, which layer disposed over and in adhering facial contactwith thin film PV cell 11 having a single light-reactive surfacedirected upward. In a flexible PV module embodiment, the PV cell 11 istypically applied or adhered directly to the integrated backsheet 14 andthe thin film photovoltaic cell 11 is effectively “encapsulated” byprotective layer 12 and integrated backsheet layer 14. Flexibleintegrated backsheet 14 in this embodiment is a second protective layerthat directly adheres to and supports the bottom surface of thin film PVcell 11 and need not be light transmitting if the surface of the thinfilm cell which it is supporting is not reactive to sunlight. Theoverall thickness of a typical rigid or flexible PV cell module willtypically be in the range of about 0.5 to about 50 mm.

In one embodiment of the invention, a PV module, as shown in FIG. 1comprises: at least one solar cell 11, typically a plurality of suchcells arrayed in a linear or planar pattern, at least one cover sheet13, typically a glass cover sheet over the front facial surface of thecell, a polymeric encapsulant material front layer 12 encapsulating thefront side of the cell, and an integrated backsheet 14 that incorporatesencapsulant material layer 14A as top facial Layer A that is in adheringcontact with both the back surface of the cell and also partially withthe polymeric encapsulant material layer 12 encapsulating the front sideof the cell. The encapsulant surface layer of the backsheet 14A exhibitsgood adhesion to both the device and the top encapsulant layer material12.

In the electronic device (and especially the PV module) embodiments ofthe present invention, the top layer or coversheet 13 and the topencapsulating layer 12 generally need to have good, typically excellent,transparency, meaning transmission rates in excess of 90, preferably inexcess of 95 and even more preferably in excess of 97, percent asmeasured by UV-vis spectroscopy (measuring absorbance in the wavelengthrange of about 250-1200 nanometers. An alternative measure oftransparency is the internal haze method of ASTM D-1003-00.

The thicknesses of all the electronic device module layers, describedfurther below, both in an absolute context and relative to one another,are not critical to this invention and as such, can vary widelydepending upon the overall design and purpose of the module. Typicalthicknesses for protective or encapsulate front layers 12 are in therange of 0.125 to 2 millimeters (mm), and for the front cover sheet inthe range of 0.125 to 1.25 mm. The thickness of the electronic devicecan also vary widely.

Light Transmitting Encapsulation Component or Layer

These layers are sometimes referred to in various types of PV modulestructures as “encapsulation” films or layers or “protective” films orlayers or “adhesive” films or layers. So long as sufficiently lighttransmitting, these layers can employ the same resins and resincompositions as described above in connection with their use as Layer Afor integrated backsheet embodiments of the present invention.Typically, these layers function to encapsulate and protect the interiorphotovoltaic cell from moisture and other types of physical damage andadhere it to other layers, such as a glass or other top sheet materialand/or a back sheet layer. Optical clarity, good physical and moistureresistance properties, moldability and low cost are among the desirablequalities for such films. Suitable polymer compositions and filmsinclude those used and in the same manner and amounts as the lighttransmitting layers used in the known PV module laminate structures,e.g., such as those taught in U.S. Pat. No. 6,586,271, US PatentApplication Publication US2001/0045229 A1, WO 99/05206 and WO 99/04971.These materials can be used as the light transmitting “skin” for the PVcell, i.e., applied to any faces or surfaces of the device that arelight-reactive.

Light Transmitting Cover Sheet

Light transmitting cover sheet layers, sometimes referred to in varioustypes of PV module structures as “cover”, “protective” and/or “topsheet” layers, can be one or more of the known rigid or flexible sheetmaterials. Alternatively to glass or in addition to glass, other knownmaterials can be employed for one or more of the layers with which thelamination films according to the present invention are employed. Suchmaterials include, for example, materials such as polycarbonate, acrylicpolymers, a polyacrylate, a cyclic polyolefin such as ethylenenorbornene, metallocene-catalyzed polystyrene, polyethyleneterephthalate, polyethylene naphthalate, fluoropolymers such as ETFE(ethylene-tetrafluoroethlene), PVF (polyvinyl fluoride), FEP(fluoroethylene-propylene), ECTFE (ethylene-chlorotrifluoroethylene),PVDF (polyvinylidene fluoride), and many other types of plastic orpolymeric materials, including laminates, mixtures or alloys of two ormore of these materials. The location of particular layers and need forlight transmission and/or other specific physical properties woulddetermine the specific material selections. As needed and possible basedupon their composition, the down conversion/light stabilizerformulations discussed above can be employed in the transparent coversheets. However, the inherent stability of some of these may not requirelight stabilization according to the present invention.

When used in certain embodiments of the present invention, the “glass”used as a light transmitting cover sheet refers to a hard, brittle,light transmitting solid, such as that used for windows, many bottles,or eyewear, including, but not limited to, soda-lime glass, borosilicateglass, sugar glass, isinglass (Muscovy-glass), or aluminum oxynitride.In the technical sense, glass is an inorganic product of fusion whichhas been cooled to a rigid condition without crystallizing. Many glassescontain silica as their main component and glass former.

Pure silicon dioxide (SiO2) glass (the same chemical compound as quartz,or, in its polycrystalline form, sand) does not absorb UV light and isused for applications that require transparency in this region. Largenatural single crystals of quartz are pure silicon dioxide, and uponcrushing are used for high quality specialty glasses. Syntheticamorphous silica, an almost 100% pure form of quartz, is the rawmaterial for the most expensive specialty glasses.

The glass layer of the laminated structure is typically one of, withoutlimitation, window glass, plate glass, silicate glass, sheet glass,float glass, colored glass, specialty glass which may, for example,include ingredients to control solar heating, glass coated withsputtered metals such as silver, glass coated with antimony tin oxideand/or indium tin oxide, E-glass, and Solexia™ glass (available from PPGIndustries of Pittsburgh, Pa.).

Laminated PV Module Structures

The methods of making PV modules known in the art can readily be adaptedto use the multilayer backsheet film structures according to presentinvention, and most advantageously employ them as an integratedbacksheet layer for PV modules. For example, the multilayer backsheetfilm structures according to present invention can be used in the PVmodules and methods of making PV modules such as those taught in U.S.Pat. No. 6,586,271, US Patent Application Publication US2001/0045229 A1,WO 99/05206 and WO 99/04971.

In general, in the lamination process to construct a laminated PVmodule, at least the following layers are brought into facial contact:

-   -   a light-receiving top sheet layer (e.g., a glass layer) having        an “exterior” light-receiving facial surface and an “interior”        facial surface;    -   a light transmitting thermoplastic polymer film having at least        one layer of light transmitting thermoplastic polymers        comprising the down conversion/light stabilizer formulations        according to present invention, having one facial surface        directed toward the glass and one directed toward the        light-reactive surface of the PV cell and encapsulating the cell        surface, provided that this layer can be optional in some module        structures where the PV cell material may be directly deposited        on the light receiving layer (e.g., glass);    -   a PV cell; and    -   an integrated backsheet layer described herein.

With the layers or layer sub-assemblies assembled in desired locationsthe assembly process typically requires a lamination step with heatingand compressing at conditions sufficient to create the needed adhesionbetween the layers and, if needed in some layers or materials,initiation of their crosslinking. If desired, the layers may be placedinto a vacuum laminator for 10 to 20 minutes at lamination temperaturesin order to achieve layer-to-layer adhesion and, if needed, crosslinkingof the polymeric material of the encapsulation element. In general, atthe lower end, the lamination temperatures need to be at least 120° C.,preferably at least 130° C., preferably at least 140° C. and, at theupper end, less than or equal to 170° C., preferably less than or equalto 160° C.

The following experiments further illustrate the invention. Unlessotherwise indicated, all parts and percentages are by weight.

Experiments

Experimental multilayer sample films (layers indicated by letters, e.g.,as A, B, and C), as summarized below in Tables below, were made usingthe thermoplastic resin materials summarized below in Table 1. The blockcomposites (BC's) and crystalline block composite (CBC's) resins used inthe experimental multilayer sample films are developmental materialsprepared as described above and are summarized in Table 2. Whereindicated, the Melt Flow Rates (MFR) are measured according to ASTMD1238 (230 C/2.16 kg) and Melt Index values (MI) are measured accordingto ASTM D1238 (190 C/2.16 kg).

TABLE 1 Resins Used in Examples Density Resin ASTM D792 Resin Productname Supplier MFR/Ml (g/cc) PP 2 D118.01 PP Dow  8.0 MFR 0.900 Plastomer1 AFFINITY ™ PL Dow  1.0 MI 0.902 1880G Plastomer 2 ENGAGE ™ Dow  5.00.870 8200 Plastomer 3 ENGAGE ™ Dow 30.0 0.902 8402

The block composites (BC's) and crystalline block copolymer composites(CBC's) below are developmental materials prepared as described aboveand are summarized in Table 2. They have the following generalcharacteristics:

i) an ethylene-based polymer (EP) that is crystalline (CEP) in CBC's;

ii) a propylene-based crystalline polymer (CPP) and

iii) a block copolymer comprising

-   -   (a) an ethylene polymer block (EB) that is a crystalline        ethylene block CEB in CBC's and    -   (b) a crystalline propylene polymer block (CPPB).

As also shown in Table 2, the BC or CBC samples are furthercharacterized by the indicated:

-   -   Wt % PP—Weight percentage propylene polymer in the BC or CBC as        measured by HTLC Separation as described above.    -   Mw—the weight average molecular weight of the BC or CBC in        Kg/mol as determined by GPC as described above.    -   Mw/Mn—the molecular weight distribution of the BC or CBC as        determined by GPC as described above.    -   Wt % C2—the weight percentage of ethylene in the CBC or BC as        determined by NMR, the balance being propylene.    -   Tm (° C.) Peak 1 (Peak 2)—Peak melting temperature as determined        by the second heating curve from DSC. Peak 1 refers to the        melting of CPPB or CPP, whereas Peak 2 refers to the melting of        CEB or CEP.    -   Tc (° C.)—Peak crystallization temperature as determined by DSC        cooling scan.    -   Heat of Fusion (J/g)—the heat of fusion of the BC or CBC        measured as described above.    -   Mol % C2—the mole percentage of ethylene in the ethylene block        or crystalline ethylene block component (iii)(a) (and also the        ethylene polymer component (1) of the BC or CBC), the balance of        comonomer in both cases being propylene.    -   Wt % CPPB in block copolymer—the weight percentage of        crystalline propylene polymer in the block copolymer component        (iii).    -   (C)BCI—the block composite index or crystalline block copolymer        composite index which reflect the content of the block        copolymer (iii) in the composition.

TABLE 2 CBC and BC Resins Used in Experimental Films Tm (° C.) Heat ofMol % Wt % Density Wt % Mw Wt % Peak 1 Tc fusion C₂ CPPB Resin MFR(g/cc) PP Kg/mol Mw/Mn C₂ (Peak 2) (° C.) (J/g) in CEB in (iii) (C)BCICBC 1 3.6 0.9055 13.2 146 2.8 46.7 130 (114) 97 126 93 50 0.729 CBC 47.0 0.9052 14.2 128 4.0 46.9 132 (108) 91 97 93 50 0.707 BC 5 4.1 0.881921.5 103 2.9 33.8 139 (40)  93 54 74 50 0.413

Several other commercially available additives and stabilizers wereemployed in the example film formulations:

-   -   White Color 1: Supplied by Ampacet Corporation as Ampacet 110456        masterbatch which contains 50% TiO2 in a 20 MI LLDPE carrier    -   White Color 2: Supplied by Ampacet Corporation as Ampacet 110443        concentrate which contains 50% TiO2 in a 8 MFR homopolymer        polypropylene    -   UV 1 & 2 (stabilizer) masterbatches: Produced by Dow Chemical        according to Table 3.    -   Vinyltrimethoxysilane (“VTMS”): Supplied by Dow Corning,        Xiameter OFS-6300 Silane    -   Peroxide: Supplied by Arkema, Luperox 101

TABLE 3 UV Stabilizer masterbatch formulations. All amounts are based onweight percent. UV 1 UV 2 Component Type of additive Supplier (Wt %) (Wt%) LDPE2 Resin Dow Chemical 89.5  PP2 Resin Dow Chemical 87.5  CyasorbUV stabilizers Cytec Industries,  1.0  UV1164 Inc Cyasorb UV stabilizersCytec Industries,  4.0  UV38535 Inc Cyasorb UV stabilizers CytecIndustries,  6.0  UV3853PP5 Inc Cyasorb UV stabilizers Cytec Industries, 2.0  UV3346 Inc Cyasorb UV stabilizers Cytec Industries,  2.0  UV3529Inc Cyasorb UV stabilizers Cytec Industries,  3.0  THT7001 Inc Uvinul5050H UV stabilizers BASF Corporation  2.0  Tinuvin 770 UV stabilizersBASF Corporation  1.0  Irganox 1010 Antioxidant BASF Corporation  0.75 0.25 Irganox 168 Antioxidant BASF Corporation  0.75

The films were prepared using the indicated processing conditions on apilot scale cast film line using a standard type of feedblockconfiguration to produce 3 layers and providing the A layer side of thefilm against cast roll.

TABLE 4 Fabrication conditions for Experimental Cast Films Pilot CastLine, Larkin 200 Midland MI Condition 1 Overall sheet thickness, mil(microns) 18 (457) Extruder (layers) A B C Layer thickness, mil(microns)     8.1    2.3    7.6 (206) (58) (193) Layer vol %  45  13  42RPM  59  18  99 Feed zone, °C. 166 193 202 Zone 2, ° C. 182 204 210 Zone3, ° C. 188 216 216 Zone 4, ° C. 193 216 216 Transfer line, screen,adapters, ° C. 193 216 216 Feedblock, ° C. 216 Die, ° C. 216 Cast roll,° C.  21 MiniCast Line, Larkin 200 Midland MI Condition 2 Overall sheetthickness, mil 28 (711) Extruder (layers) A B C Layer thickness, mil   18.2    2.0     7.8 (462) (51) (198) Layer vol %  65   7  28 RPM  41 25  99 Feed zone, ° C. 166 193 202 Zone 2, ° C. 182 204 210 Zone 3, °C. 188 216 216 Transfer line, screen, adapters, ° C. 193 193 193Feedblock, ° C. 210 Die, ° C. 210 Cast roll, ° C.  21

Silane grafted polyethylene is produced and added as a concentrate inLayer A. The final concentration of the polymers, peroxide and silaneare given for films 1 through 4 in Table 5. The films are prepared andtested for their sealing and interlayer strengths. The two A (top)layers are sealed together by heat sealing at 204° C. for 10 seconds at30 psi (207 kPa, 2.07 bar) pressure. The films are thus sealed asCBA-ABC. The sealed films 3 and 4 are then aged for two weeks in an oventhat is maintained at 85° C. and 85% relative humidity. Sealing testsare performed on aged films by a peel strength test according to ASTMF88/8F88-09 for 180° peel at 23° C. on an INSTRON® tester (model 5500R)at 50 mm gap at a rate of 50 mm/min. Peel strengths are recorded inTable 6, below. For films exhibiting a delamination failure, thelocation of the delamination is noted and the sample is tested in theINSTRON tester in a similar manner but by peeling the film layers thatare then separating by delamination. This second peel test is theinterlayer adhesion strength test done at 23° C. The layers thatdelaminate are recorded along with their interlayer adhesion strengthvalues.

In some cases, the entire film thickness breaks, as the only failure andthere is no delamination failure observable. In those cases, all theinterlayer adhesion strength values are clearly excellent but there isno interlayer adhesion strength value measurable or recorded.

TABLE 5 Summary of Experiment Cast Film Formulations 1 and 2 (given inwt %). Experimental Film No. 1 2 3 4* Layer # A B C A B C A B C A B CPP2 72 82 82 82 Plastomer 1 10 CBC1 80 CBC4 80 BC5 80 Plastomer 3 18.618.6 18.6 18.6 18.6 Silane 0.90 0.90 0.90 0.90 0.90 Peroxide 0.045 0.0450.045 0.045 0.045 Plastomer 2 75.4 75.4 75.4 75.4 75.4 UV-1 5.0 5.0 5.05.0 5.0 UV-2 10 10 10 10 Color 1 20 20 20 8 8 Color 2 8 8 Fab Condition1 2 2 2 *Comparative Experiment - not an example of the presentinvention.

TABLE 6 Peel test results Experimental Film No. 1 2 3 4* Seal-seal (A-A)peel Average seal strength, N/cm 64.6 73.7 59.7 13.8 Interlayer peelPercent of samples with no delamination 100% 100% 100% 0% Location ofinterlayer delamination — — — B-C Average interlayer strength of No NoNo 2.3 delaminating samples, N/cm delam delam delam

The film examples prepared according to the present invention allexhibit excellent interlayer strength. In comparative Experimental Film4, the B layer is omitted, the encapsulant layer is applied directly tothe bottom polypropylene layer and seal strength and interlayer adhesionare greatly reduced.

Miscellaneous

Unless stated to the contrary, implicit from the context, or customaryin the art, all parts and percents are based on weight and all testmethods are current as of the filing date of this disclosure. Forpurposes of United States patent practice, the contents of anyreferenced patent, patent application or publication are incorporated byreference in their entirety (or its equivalent US version is soincorporated by reference) especially with respect to the disclosure ofsynthetic techniques, definitions (to the extent not inconsistent withany definitions specifically provided in this disclosure), and generalknowledge in the art.

The numerical ranges in this disclosure are approximate, and thus mayinclude values outside of the range unless otherwise indicated.Numerical ranges include all values from and including the lower and theupper values, in increments of one unit, provided that there is aseparation of at least two units between any lower value and any highervalue. As an example, if a compositional, physical or other property orprocess parameter, such as, for example, molecular weight, viscosity,melt index, temperature, etc., is from 100 to 1,000, it is intended thatall individual values, such as 100, 101, 102, etc., and sub ranges, suchas 100 to 144, 155 to 170, 197 to 200, etc., are expressly enumerated.For ranges containing values which are less than one or containingfractional numbers greater than one (e.g., 1.1, 1.5, etc.), one unit isconsidered to be 0.0001, 0.001, 0.01 or 0.1, as appropriate. For rangescontaining single digit numbers less than ten (e.g., 1 to 5), one unitis typically considered to be 0.1. These are only examples of what isspecifically intended, and all possible combinations of numerical valuesbetween the lowest value and the highest value enumerated, are to beconsidered to be expressly stated in this disclosure. Numerical rangesare provided within this disclosure for, among other things, density,melt index and relative amounts of components in various compositionsand blends.

The term “comprising” and its derivatives are not intended to excludethe presence of any additional component, step or procedure, whether ornot the same is specifically disclosed. In order to avoid any doubt, anyprocess or composition claimed through use of the term “comprising” mayinclude any additional steps, equipment, additive, adjuvant, or compoundwhether polymeric or otherwise, unless stated to the contrary. Incontrast, the term, “consisting essentially of” excludes from the scopeof any succeeding recitation any other component, step or procedure,excepting those that are not essential to operability. The term“consisting of” excludes any component, step or procedure notspecifically delineated or listed. The term “or”, unless statedotherwise, refers to the listed members individually as well as in anycombination.

Although the invention has been described in considerable detail throughthe preceding description and examples, this detail is for the purposeof illustration and is not to be construed as a limitation on the scopeof the invention as it is described in the appended claims.

What is claimed is:
 1. A multilayer film structure comprising: a topencapsulation Layer A; a bottom Layer C comprising a propylene-basedpolymer having at least one melting point greater than 125° C.; a tieLayer B between Layer A and Layer C; the multilayer film structurecharacterized in that Layer B consists of (1) a block composite resin(BC), (2) an optional polyolefin consisting of ethylene and α-olefin,(3) an optional colorant, (4) an optional stabilizer, and (5) anoptional antioxidant, the BC made from monomers consisting of propyleneand ethylene and the BC has i) an ethylene-propylene copolymer (EP)comprising at least 40 mol % polymerized ethylene; ii) a crystallinepropylene-based polymer (CPP); and iii) a diblock copolymer comprising(a) an ethylene-propylene block comprising at least 40 mol % polymerizedethylene and (b) a crystalline propylene block.
 2. The multilayer filmstructure of claim 1 wherein the CPP comprises greater than 90 mol %polymerized propylene.
 3. The multilayer film structure of claim 2wherein the block composite resin in Layer B has two peak meltingtemperatures.
 4. The multilayer film structure of claim 3 wherein theblock composite resin in layer B has a first peak melting temperaturegreater than 120° C.
 5. The multilayer film structure of claim 4 whereinthe block composite resin in layer B has a first peak meltingtemperature greater than 125° C.
 6. The multilayer film structure ofclaim 1 wherein the crystalline propylene block (iii)(b) of the diblockcopolymer is the same composition as the crystalline propylene-basedpolymer (CPP) of the block composite resin.
 7. The multilayer filmstructure of claim 6 wherein the ethylene-propylene block (iii)(a) ofthe diblock copolymer is the same composition as the EP copolymer of theblock composite resin.
 8. The multilayer film structure of claim 1wherein the Layer B block composite resin has an ethylene-propyleneblock amount in the range of from 30 to 70 weight % based on totalweight of the diblock copolymer (iii).
 9. The multilayer film structureof claim 1 wherein the block composite resin has a CBCI from 0.3 to 0.8.10. The multilayer film structure of claim 1 wherein the tie Layer B isa blend with greater than 40 weight percent of the block compositeresin.
 11. The multilayer film structure of claim 1 wherein the topencapsulation Layer A comprises an ethylene/octene copolymer elastomeror plastomer.
 12. The multilayer film structure of claim 11 wherein thetop encapsulation Layer A comprises a silane-graft containingethylene/octene copolymer.
 13. The multilayer film structure of claim 1comprising the top seal Layer A comprising a silane-graft containingethylene/alpha-olefin copolymer; the bottom Layer C comprising thepropylene-based polymer; and the tie Layer B between Layer A and LayerC, the block composite resin with i) an ethylene-propylene polymer (EP)comprising at least 93 mol % polymerized ethylene; ii) the crystallinepropylene-based polymer; and iii) a diblock copolymer comprising (a) anethylene-propylene block comprising at least 93 mol % polymerizedethylene and (b) a crystalline propylene block.
 14. The multilayer filmstructure of claim 1 having a thickness from 0.2 mm to 1.5 mm whereinthe top encapsulation Layer A is from 0.15 mm to 1.25 mm in thickness;the tie Layer B is from 10 to 150 μm in thickness; and Layer C is from150 to 375 μm in thickness.
 15. An electronic device (ED) modulecomprising an electronic device and a multilayer film structure ofclaim
 1. 16. The multilayer film structure of claim 1 wherein the Layer(B) consists of (1) the BC, (2) the colorant, (3) the stabilizer that isa UV stabilizer, and (4) the antioxidant.
 17. The multilayer filmstructure of claim 1 wherein the Layer (B) consists of (1) the BC, (2)the colorant, and (3) the stabilizer that is a UV stabilizer.
 18. Themultilayer film structure of claim 1 wherein the Layer (B) consists of(1) the BC, and (2) the colorant.